Thursday, 07 March 2019 14:10

Summer Scholar Update: Erica E. Eggleton

Erica Eggleton Sample 6515 DP March 2019

2016 MIT Summer Scholar Erica Eggleton worked in the lab of MIT Professor Krystyn Van Vliet on lithium manganese oxide (LMO) electrodes for lithium ion batteries. Here, she measures out carbon powder, a binder, and LMO, the active powder used in the battery electrodes. Photo, Denis Paiste, MIT Materials Research Laboratory.

What graduate program are you currently pursuing?

I am a second-year PhD student in the Chemical Engineering Department at the University of Washington.

Have you had any articles published related to your MIT Summer Scholar experience?

I was one of the co-authors of a February 2017 report in Advanced Energy Materials by first author Frank Grogan and senior author Krystyn Van Vliet, the Michael (1949) and Sonja Koerner Professor of Materials Science and Engineering and Associate Provost at MIT. This paper reported on the mechanical properties of a sulfide-based solid electrolyte material and its performance when incorporated into lithium-ion batteries. I contributed to this work as a Summer Scholar through MIT Materials Research Laboratory’s National Science Foundation Research Experience for Undergraduate (REU) program.

University of Washington chemical engineering graduate student Erica Eggleton interned as an MIT Summer Scholar during 2016.

What awards have you received?

I was one of the graduate students selected as a 2019 Clean Energy Institute Fellow and a National Science Foundation Research Trainee (NRT) in data science at the University of Washington. These awards enable my current research on developing a battery and vehicle model to predict the state of health of lithium-ion battery packs in King County Metro’s hybrid electric bus fleet using geographic information system (GIS) data.

What about your MIT Summer Scholar experience was most enjoyable?

One of the most memorable and inspiring moments from my experience was touring various labs around MIT's campus and learning about the vast amount of research being done.

How did your MIT Summer Scholars experience contribute to getting you where you are today?

The MIT Summer Scholars program reassured me that I wanted to go to graduate school. I had the opportunity to form connections with people at MIT and with the other scholars from across the country. I also got valuable hands-on experience with various experimental techniques and contributed to a publication.

What are your future plans or ambitions?

My future ambitions are driven by my passion for advancing clean energy technologies. I currently imagine doing this through teaching and advocating for science policy.

back to newsletterWatch videos of 2018 MIT MRL Summer Scholars.

Friday, 17 April 2020 11:31

Summer Scholar Update: Jared Bowden

2019 Summer Scholar Jared Bowden will pursue a PhD at the University of California, Berkeley.

During Summer 2019, Jared Bowden worked on slow release, targeted drug delivery in the lab of MIT Professor Paula T. Hammond, who is head of the department of chemical engineering and the David H. Koch (1962) Professor in Engineering, through the NSF-funded MIT MRL Research Experience for Undergraduates program.

What graduate school program do you intend to pursue?

After graduating from the University of Massachusetts, Amherst, this spring, I will be pursuing my PhD in Chemical and Biochemical Engineering at the University of California, Berkeley, next fall. I am really excited to continue my studies and grateful for all of the people and experiences which have helped me along the way to get to this point.

What about your MIT MRL Summer Scholar experience was most enjoyable?

The MIT MRL Summer Scholar program allowed me to dive more in depth into a research project than I had ever had the ability to do before and I really enjoyed the freedom I had to take on the project as my own and lead its direction. This experience was also instrumental in helping me decide to continue my studies in graduate school.

What are your future plans or ambitions?

I am really interested in continuing to conduct research with applications in improving human and environmental health, whether it be through an academic path beyond graduate school or in industry.

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Wednesday, 06 February 2019 10:35

Summer Scholar Update: Katharine Greco

Summer Scholar Katharine Greco Spain January 2019 Web
MIT Chemical Engineering graduate student Katharine Greco spent the 2019 Independent Activities Period (IAP) conducting research in the Molecular Nanotechnology Lab at the University of Alicante in Spain. Her work is part of a collaboration to develop next generation electrodes for redox flow batteries.

What graduate program are you currently pursuing?
I am pursuing a PhD in Chemical Engineering at MIT, and have already earned my Master's degree in Chemical Engineering Practice (MSCEP). I am currently studying transport in flow battery electrodes in the Brushett group.

What awards have you received?
I was a Presidential Scholar coming in to MIT. I also have a National Science Foundation Graduate Research Fellowship.

What about your MIT Summer Scholar experience was most enjoyable?
I really enjoyed working closely with graduate students in ARCO Career Development Professor William A. Tisdale’s lab and becoming part of the group for the summer. I also relished the chance to conduct independent research. This experience greatly contributed to my decision to pursue a graduate degree. 

Katharine Greco Hood 3369 July 2015 DP Web

Katharine Greco works with a three–necked flask for synthesizing core/shell quantum dots in the Tisdale Lab during her 2015 Summer Scholar internship. Greco synthesized up to 16 samples of quantum dots each week. Photo, Denis Paiste, Materials Research Laboratory.

How did your MIT Summer Scholars experience contribute to getting you where you are today?

The Summer Scholars program allowed me to expand my network at MIT, which I believe was a huge factor in my acceptance here. Additionally, my positive experience during the program encouraged me to come back for graduate school.

What are your future plans or ambitions?
I would like to work on the edge of research and industry by helping to deploy clean energy technologies.

back to newsletterWatch videos of 2018 MIT MRL Summer Scholars.

Thursday, 16 April 2020 11:38

Summer Scholar Update: Leah Borgsmiller

2019 MIT MRL Summer Scholar Leah Borgsmiller chooses Northwestern University for graduate school. 

During Summer 2019, Leah Borgsmiller worked on niobium-aluminum thin films for superconducting nanowire single photon detectors in Electrical Engineering and Computer Science Professor Karl K. Berggren’s lab through the NSF-funded MIT MRL Research Experience for Undergraduates program.

What graduate school will you be attending?

I have decided to continue my studies at Northwestern University by starting in their PhD program in Materials Science and Engineering in the fall. I’m not completely sure what I want to do in the future, but I’m confident that I want to pursue a PhD in the area of electronic materials and then build a career in materials research.

What awards have you received?

I received the Northwestern University Outstanding MSE Junior Award in May of 2019. I have also been awarded a National Science Foundation Graduate Research Fellowship to fund my graduate studies.

What about your MIT MRL Summer Scholar experience was most enjoyable?

The most enjoyable part of my summer experience at MIT was being exposed to so many different cutting edge researchers and studies being conducted at MIT. I loved hearing about what my peers were researching during their time at MIT in addition to getting the opportunity to dive deeply into my project.

How did your Summer Scholars experience contribute to getting you where you are today?

The MIT MRL Summer Scholars experience confirmed that I wanted to apply to graduate schools and has given me a new confidence in myself as a researcher, as well as providing me with practical research skills that have helped me in research projects since then. This experience was invaluable in preparing me to start my PhD in the fall.

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Wednesday, 06 February 2019 10:47

Summer Scholar Update: Olivia Fiebig

Summer Scholar Olivia Fiebig July 2015 DP
Olivia Fiebig prepares a sample for fast protein liquid chromatography in Associate Professor of Chemical Engineering Bradley D. Olsen’s lab as part of her Summer Scholars experience in 2015. Photo, Denis Paiste, Materials Research Laboratory.

What graduate program are you currently pursuing?
I’m pursuing a Ph.D. in physical chemistry at MIT. As a member of the Schlau-Cohen lab, I use ultrafast spectroscopy to study energy transfer processes in photosynthetic systems.

What awards have you received?
At my undergraduate institution, I received the Rowan University Award for Excellence in Undergraduate Research and the Dean’s Outstanding Senior Award in Chemistry. As a graduate student at MIT, I received a National Science Foundation Graduate Research Fellowship.

Olivia Fiebig Headshot January 2019

What about your MIT Summer Scholar experience was most enjoyable?
I loved learning new techniques in the Olsen lab and exploring Boston and Cambridge with the other Summer Scholars.

How did your MIT Summer Scholars experience contribute to getting you where you are today?
My experience as a Summer Scholar confirmed that I enjoy research, and I decided that I wanted to continue it by attending graduate school. I also fell in love with MIT and Boston and was thrilled to be offered the opportunity to return to MIT as a graduate student in the Department of Chemistry.

What are your future plans or ambitions?
I want to become a professor to pursue my passion for teaching and give students the opportunity to explore research.

back to newsletterWatch videos of 2018 MIT MRL Summer Scholars.

Friday, 25 January 2019 14:11

Summer Scholar Update: Sarah Arveson

Sarah Arveson 0199 Scope Yale 2019 Web
2014 Summer Scholar Sarah M. Arveson peers into a microscope at Yale University, where she is a graduate student in geology and geophysics. Arveson spent her NSF REU at MIT in the lab of ARCO Career Development Professor William A. Tisdale working on methyl ammonium lead bromide thin films. Courtesy photo.

What graduate program are you currently pursuing?

Since my MIT REU experience, I graduated from UC Berkeley in 2015 with a B.A. in Applied Mathematics and Geophysics with High Honors. I am currently pursuing a PhD in the Department of Geology & Geophysics at Yale University. I conduct high-pressure and high-temperature experiments to understand the interior of Earth and other planets.

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Have you had any articles published related to your MIT Summer Scholar experience?
I am a second author on the following paper, which features experimental results from my MIT REU: Tyagi, P., Arveson, S. M., & Tisdale, W. A. (2015). Colloidal organohalide perovskite nanoplatelets exhibiting quantum confinement,The Journal of Physical Chemistry Letters, 6(10), 1911-1916.

What awards have you received?

I have received the following awards:

• Charles H. Ramsden Scholarship (Department of Earth and Planetary Science, UC Berkeley - 2015)

• Graduate Student Research Grant (Geological Society of America - 2017)

• Graduate Fellowship Research Grant (NASA CT Space Grant Consortium - 2017)

• Hammer Prize (Department of Geology & Geophysics, Yale University - 2018)

• Graduate Fellowship Research Grant (NASA CT Space Grant Consortium - 2018)

• Dean’s Emerging Scholar Research Award (Yale University - 2018)

• Outstanding Student Presentation Award – Mineral and Rock Physics (American Geophysical Union – 2018)

Sarah Arveson Yale 2019 SQ Web

What about your MIT Summer Scholar experience was most enjoyable?
I enjoyed getting to explore an area of research that was new to me, meeting people from different programs from all over the country, and exploring a new city.

How did your MIT Summer Scholars experience contribute to getting you where you are today?
I enjoyed my research experience with MIT MPC/CMSE so much that when applying for graduate school, I was torn between remaining in Earth Science or starting a Materials Science PhD. I ultimately chose an Earth Science program, but my thesis is heavily materials science influenced. The knowledge I gained over the summer studying organometallic halide perovskites for solar cell applications gives me a broader perspective on my own research today. For instance, the first publication from my PhD is on defect-induced semiconducting states in potassium bromide (KBr) at high-pressure (Arveson, S. M., Kiefer, B., Deng, J., Liu, Z., & Lee, K. K. (2018), Thermally induced coloration of KBr at high pressures, Physical Review B, 97(9), 094103). This phenomenon has been robustly observed in the high-pressure experimental community but had not been previously characterized. My experience from the MIT MPC/CMSE program gave me the tools to do so. (Editor’s note: MPC and CMSE became the Materials Research Laboratory in October 2017.)

What are your future plans or ambitions?
After my PhD, I would like to continue working in high-pressure experimental research in the public sector, either in an academic setting or at a national lab. My interests also include science communication, science policy, and labor organizing.

back to newsletterWatch a video of Sarah Arveson’s MIT 2014 summer internship.

Watch videos of 2018 MIT MRL Summer Scholars.

Research Experience for Undergraduates program participants bring diverse interests in sustainable energy, polymers and physics
2019 MRL Summer Scholars are (top row, l-r) Isabel Albelo, Leah Borgsmiller, Jared  Bowden, Clement Ekaputra, and Ewell Nathan, and (bottom row, l-r) Marcos Logrono, Chris  Moore, Ariane Marchese, Melvin Nunez Santiago and Carly Tymm.
 2019 MRL Summer Scholars are (top row, l-r) Isabel Albelo, Leah Borgsmiller, Jared Bowden, Clement Ekaputra, and Nathan Ewell, and (bottom row, l-r) Marcos Logrono, Chris Moore, Ariane Marchese, Melvin Nunez Santiago and Carly Tymm.

A diverse group, with a broad range of personal and scientific interests and experiences, this year’s 10 MIT Materials Research Laboratory Summer Scholars include a former Navy Seal, an accomplished classical pianist and a voice actor. Each was selected for a strong undergraduate record in science and technology.

The Summer Scholars, as MRL calls its National Science Foundation funded Research Experience for Undergraduates interns, will be on the MIT campus from June 16 to Aug. 10, 2019. They were chosen from among 286 applicants.

“I was a Navy SEAL for nine years in which time I was deployed to Iraq and Afghanistan as well as serving as a mountaineering instructor in Kodiak, Alaska,” says University of Washington junior Chris Moore. While in Alaska, Moore and two fellow SEAL instructors planned and executed an expedition to the summit of Denali (formerly Mount McKinley).

Clement N. Ekaputra, a Case Western Reserve University junior, plays classical piano and recently performed a concerto as a soloist with the University of Pittsburgh symphony orchestra.

When she isn’t pursuing her scientific education, Hunter College physics major Ariane Marchese is a voice actress and volunteers to give voice to audiobooks for schools.

Eager learners

While seeking a sharper focus for graduate school research is a common theme for Summer Scholars, this year’s participants are eager learners willing to stretch into new topics and experimental techniques. “I’m really excited to learn from MIT Materials Research Lab faculty and the other talented and diverse interns I’ll be working with,” Marchese says.

University of Puerto Rico - Mayaguez mechanical engineering major Marcos A. Logrono Lopez hopes to pursue research at MIT in the area of microfluidics. “My goal is to understand the behaviors that dominate fluids at the micro scale and implement them into new innovative technologies such as micro-propulsion and micro-electromechanical systems,” he says.

“I’m certain that no matter the project I’m assigned to in this internship, I will work passionately and be motivated with the goal of pushing forward the research that takes place at MIT,” Logrono says. “Positivism, humbleness, hard work, respectfulness and passion for helping others are the fundamental bases of who I am as a person,” he adds.

University of California - Los Angeles junior materials science and engineering major Isabel Albelo hopes the REU experience “will provide me with further clarity as to what I would like to study in graduate school and the field in which I would like to work.” She is currently interested in sustainability, either in the areas of agriculture and food science or renewable energy generation and storage. During the first half of 2018, Albelo studied abroad in Chile despite the difficulty of fitting that experience into an engineering curriculum.

Case Western Reserve University junior Nathan Ewell is most interested in electrochemical engineering and polymer physics. “I am excited to get a feel for what my life will be like as a graduate student in a few years,” he says.

Also interested in polymers and nanomaterials, University of Massachusetts Amherst chemical engineering major Jared Bowden hopes to work with bio-inspired materials. “I am very interested in emulating extremely specialized natural polymers perfected by millions of years of natural selection and applying the benefits of their properties to modern problems,” Bowden says. Additionally, says Bowden, “I hope to learn new things that I can bring back with me to UMass that will help me in my nanofiber research for my senior thesis.”

Moore, a physics and astronomy major, hopes to conduct optical experimental research in condensed matter, specifically topological defects. “I find the field fascinating both conceptually and experimentally,” Moore says. “Much of what appeals to me about the research at MIT is how often it creates and broadens new fields of research. This is reflective of the clear experimental direction that I hope to pick up during this experience.”

Melvin Núñez Santiago is majoring in electrical technology with renewable energy at the University Ana G. Mendez at Gurabo in Puerto Rico. Núñez hopes to channel his passion for research and technology development into a summer project related to electronics, power, communications or energy storage. Marchese, a junior at Hunter College, also expresses interest in energy production and storage but is interested in all aspects of materials science.

Improving their research and analytical skills is a common goal of this year’s cohort. “By working full-time on a research project with them, I know I will learn a lot about conducting research – about discovering interesting questions and designing methods to solve them,” says Ekaputra, a Case Western Reserve materials science and engineering major.

Dartmouth College junior Carly Tymm says, “I would like to take on a multidisciplinary project at MIT with perspectives from synthetic chemistry, surface science and bioengineering in the design, synthesis and analysis of biomaterials. There are many macromolecular solutions to challenges in medicinal materials science that I would like to investigate deeper.” Tymm is a double major in chemistry and biomedical engineering sciences.

Regional explorations

Northwestern University junior materials science and engineering major Leah Borgsmiller will be experiencing Massachusetts for the first time, “so I am excited to spend evenings and weekends exploring the Cambridge/Boston area,” she says. She hopes the intensive eight-week program will help her form long-lasting connections to her peers as well as MIT faculty.

“In this modern world, we are increasingly more dependent on electronics and energy consumption to power our lives, and so being able to contribute to research to make these processes more efficient and environmentally-friendly would be a rewarding experience,” Borgsmiller says.

back to newsletter Denis Paiste, Materials Research Laboratory
April 26, 2019

Tuesday, 28 August 2018 14:30

Summer Scholars Poster Session 2018

MIT MRL summer interns tackled materials science and other research challenges, contributing to MIT faculty research labs, overcoming obstacles and gaining new skills. They presented their results at a Poster Session on Wednesday, Aug. 8, 2018.

 

back to newsletterRead more about 2018 Summer Scholar research At the forefront of new technology.

View Summer Scholars videos on our YouTube channel.

High-temperature steam might be used in remote regions to cook, clean, or sterilize medical equipment.

MIT engineers have built a device that soaks up enough heat from the sun to boil water and produce “superheated” steam hotter than 100 degrees Celsius, without any expensive optics.

On a sunny day, the structure can passively pump out steam hot enough to sterilize medical equipment, as well as to use in cooking and cleaning. The steam may also supply heat to industrial processes, or it could be collected and condensed to produce desalinated, distilled drinking water.

MIT Solar Steam PRESS web
In this experiment, the new steam-generating device was mounted over a basin of water, placed on a small table, and partially surrounded by a simple, transparent solar concentrator. The researchers measured the temperature of the steam produced over the course of the test day, Oct. 21, 2017. Courtesy of the researchers

The researchers previously developed a sponge-like structure that floated in a container of water and turned the water it absorbed into steam. But a big concern is that contaminants in the water caused the structure to degrade over time. The new device is designed to be suspended over the water, to avoid any possible contamination.

The suspended device is about the size and thickness of a small digital tablet or e-reader, and is structured like a sandwich: The top layer is made from a material that efficiently absorbs the sun’s heat, while the bottom layer efficiently emits that heat to the water below. Once the water reaches the boiling point (100 C), it releases steam that rises back up into the device, where it is funneled through the middle layer — a foam-like material that further heats the steam above the boiling point, before it’s pumped out through a single tube.

“It’s a completely passive system — you just leave it outside to absorb sunlight,” says Thomas Cooper, assistant professor of mechanical engineering at York University, who led the work as a postdoc at MIT. “You could scale this up to something that could be used in remote climates to generate enough drinking water for a family, or sterilize equipment for one operating room.”

The team’s results are detailed in a paper published December 11, 2018,  in Nature Communications. The study includes researchers from the lab of Gang Chen, the Carl Richard Soderberg Professor of Power Engineering at MIT.

A clever combination

In 2014, Chen’s group reported the first demonstration of a simple, solar-driven steam generator, in the form of a graphite-covered carbon foam that floats on water. This structure absorbs and localizes the sun’s heat to the water’s surface (the heat would otherwise penetrate down through the water). Since then, his group and others have looked to improve the efficiency of the design with materials of varying solar-absorbing properties. But almost every device has been designed to float directly on water, and they have all run into the problem of contamination, as their surfaces come into contact with salt and other impurities in water.

The team decided to design a device that instead is suspended above water. The device is structured to absorb short-wavelength solar energy, which in turn heats up the device, causing it to reradiate this heat, in the form of longer-wavelength infrared radiation, to the water below. Interestingly, the researchers note that infrared wavelengths are more readily absorbed by water, versus solar wavelengths, which would simply pass right through.

For the device’s top layer, they chose a metal ceramic composite that is a highly efficient solar absorber. They coated the structure’s bottom layer with a material that easily and efficiently emits infared heat. Between these two materials, they sandwiched a layer of reticulated carbon foam — essentially, a sponge-like material studded with winding tunnels and pores, which retains the sun’s incoming heat and can further heat up the steam rising back up through the foam. The researchers also attached a small outlet tube to one end of the foam, through which all the steam can exit and be easily collected.

Finally, they placed the device over a basin of water and surrounded the entire setup with a polymer enclosure to prevent heat from escaping.

“It’s this clever engineering of different materials and how they’re arranged that allows us to achieve reasonably high efficiencies with this noncontact arrangement,” Cooper says.

Full steam ahead

The researchers first tested the structure by running experiments in the lab, using a solar simulator that mimics the characteristics of natural sunlight at varying, controlled intensities. They found that the structure was able to heat a small basin of water to the boiling point and produce superheated steam, at 122 C, under conditions that simulated the sunlight produced on a clear, sunny day. When the researchers increased this solar intensity by 1.7 times, they found the device produced even hotter steam, at 144 C.

On Oct. 21, 2017, they tested the device on the roof of MIT’s Building 1, under ambient conditions. The day was clear and bright, and to increase the sun’s intensity further, the researchers constructed a simple solar concentrator — a curved mirror that helps to collect and redirect more sunlight onto the device, thus raising the incoming solar flux, similar to the way a magnifying glass can be used to concentrate a sun’s beam to heat up a patch of pavement.

With this added shielding, the structure produced steam in excess of 146 C over the course of 3.5 hours. In subsequent experiments, the team was able to produce steam from sea water, without contaminating the surface of the device with salt crystals. In another set of experiments, they were also able to collect and condense the steam in a flask to produce pure, distilled water.

Chen says that, in addition to overcoming the challenges of contamination, the device’s design enables steam to be collected at a single point, in a concentrated stream, whereas previous designs produced more dilute spray.

“This design really solves the fouling problem and the steam collection problem,” Chen says. “Now we’re looking to make this more efficient and improve the system. There are different opportunities, and we’re looking at what are the best options to pursue.”

This research was supported in part by MIT’s Abdul Latif Jameel Water and Food Systems Lab (J-WAFS), and from MIT’s S3TEC Center, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Basic Energy Sciences, and by an Early Postdoc Mobility Fellowship from the Swiss National Science Foundation.

– Jennifer Chu | MIT News Office back to newsletter
December 11, 2018

MIT researchers use Resonant X-Ray Scattering measurements to reveal unexpected “Wigner glass” in desirable superconducting material.
MIT MRL Wigner Glass Mingu Kang Web

Illustration shows the disordered, or “glassy,” arrangement of electrons, known as a “Wigner glass,” in experiments on ultra-thin copper-oxide ceramic superconductors performed by MIT researchers. The “Fourier space,” or momentum space, image at left shows the diffraction data that proved the tendency of the charge ripples to align in any direction, while the image at right displays the random placement of electrons in “real space.” The finding was unexpected as previous experiments found that electrons prefer to spatially organize along the crystallographic direction connecting the copper and oxygen atoms in the material. Image, Min Gu Kang

Cuprates, a class of copper-oxide ceramics that share a common building block made of copper and oxygen atoms in a flat square lattice, have been studied for their ability to host superconductivity at record-high temperatures above 100 kelvins. In their pristine state, however, they are a special kind of insulator known as a Mott insulator. 

When extra electrical carriers (electrons or holes) are added to an insulator, a process called doping, the insulator may become a metal or a semiconductor, the very material that modern electronic technologies are built on. Cuprates, however, behave neither like a normal insulator nor like a normal metal because of strong interactions between their electrons. To avoid the large energy cost arising from these interactions, the electrons spontaneously organize in a collective state where the motion of each particle is tied to all the other ones. 

One example is the superconducting state, where electrons move in unison and drift with zero net friction when a potential is applied, a zero-resistance state which is a defining characteristic of a superconductor. Another collective electronic state is a “charge density wave,” a term coined from the wave-like modulation in the density of electrons, in which electrons “freeze” into periodic and static patterns, at the same time hindering electron flow.  This state is therefore antagonistic to the superconducting state, and, therefore, important to study and understand.  In cuprates, charge-density-waves prefer to align to the atomic rows of copper and oxygen atoms that make up the underlying crystal structure, with wave “‘crests” occurring every 3 to 5 unit cells, depending on the  material and doping level.

Using resonant X-ray scattering to study these charge-density-waves in two different cuprate compounds, neodymium copper oxide (Nd2CuO4 or NCO) and praseodymium copper oxide (Pr2CuO4 or PCO) doped with extra electrons, MIT researchers made an unexpected discovery. Their work revealed a phase of the material where the electrons fall into a disordered, or “glassy,” arrangement, dubbed a “Wigner glass.” The results are published  in a paper in Nature Physics.

Resonant X-ray scattering is a recently developed diffraction technique to perform crystallography on the electrons rather than exclusively on the atoms as in conventional X-ray diffraction. “In the limit of low concentration of doped electrons, we observed a completely new and unexpected form of electronic phase which is neither a superfluid nor a crystal, but it rather has the characteristics of a Wigner glass. In this phase, the electrons form a collective state without any orientational preference,” says the paper’s senior author Riccardo Comin, Assistant Professor of Physics at MIT. Such an amorphous glass of electrons is completely unprecedented in this family of materials, he adds. 

This phenomenon emerges only in a narrow window of electron doping. “Intriguingly, this exotic new state only exists in a small region of the electronic phase diagram of this material, and when more electrons are doped in the CuO2 (copper oxide) planes, a more conventional electronic crystal is recovered, whose ripples align to the crystallographic axes of the underlying atomic lattice,” Min Gu Kang, the paper’s lead author, explains.

The MIT team, consisting of Comin, graduate student Kang, and postdoc Jonathan Pelliciari, designed the project and led the majority of experiments. Their research was made possible by the contributions of researchers at various institutions and facilities worldwide. Resonant X-ray scattering measurements were performed at multiple synchrotron facilities including the Berlin Electron Storage Ring in Germany, the Canadian Light Source in Saskatoon, Saskatchewan, Canada, and the Advanced Light Source, in Berkeley, Calif. The copper-oxide thin film samples were grown at NTT Basic Research Laboratories, Japan. Theoretical analysis was developed by researchers at the Indian Institute of Science, India.

Comin notes that the proposed theory explains the role of the electronic band structure in governing the periodic spacing and lack of orientational preference of the density waves as a function of doping level in this material. “Our theory suggests that these electronic ripples are initially formed with irregular shapes and are likely nucleated around defects or impurities in the material,” Comin says.  “When the density of carriers increases, the electrons manage to find a more highly-ordered arrangement that minimizes the total energy of the system, thereby restoring the more conventional charge density waves that have been observed universally in all families of copper-oxide superconductors.”

“I was completely blown away by Riccardo's results on NCO and PCO,” says Peter Abbamonte, Fox Family Professor in Engineering at the University of Illinois at Urbana-Champaign, who developed the resonant soft X-ray scattering technique. Noting that charge density wave (CDW) order in cuprates has been at the center of the field for well over a decade, Abbamonte, who was not involved in this research, explains that the previous understanding has been that the CDW order is pinned to the crystal lattice, meaning the charge density wave must point in either of two perpendicular directions, but nowhere in between. This conventional wisdom is built on two decades of resonant scattering and scanning tunneling microscopy (STM) experiments that have always found this to be the case, he notes.

Comin’s research on these particular electron-doped cuprates showed that during the glassy phase the charge order can point in any direction, independent of the crystal lattice it lives in. “The more precise statement is that the CDW order parameter is not Ising-like (that is, taking only discrete values, in this case two: x or y), as has always been assumed, but is more like an X-Y order parameter (that is, free to choose any value on a continuous range, such as all directions between x and y as is the case here) that is only weakly influenced by the crystal,” Abbamonte says.
 
“It is going to take some time for the community to fully digest this realization and its implications for understanding the relevance of CDW order,” Abbamonte adds. “What is clear is Riccardo's paper is going to lead to a serious re-reckoning of the rules of the game, and in this sense is a major advance for the field.” 

Superconductors have an immense, largely untapped potential for transformative applications such as quantum computing, lossless energy transport, magnetic sensing and medical diagnostic imaging, and plasma and nuclear fusion power technologies.

“Overall, our study has revealed yet another manifestation of the exquisite quantum character of charge carriers in high-temperature superconductors, which ultimately arises from the nature of the electronic interactions,” Comin says. “The detailed behavior of electrons uncovered in this work provides new insights on how high-temperature superconductivity is born out of a Mott insulator, and promises to bridge a gap between regions of the phase diagram with very contrasting phenomenologies.” 

This work is supported by the National Science Foundation under Grant No. 1751739.

back to newsletterMaterials Research Laboratory
Updated May 1, 2019

 

 

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