Summer Scholar Stephanie Bauman interns in Luqiao Liu lab synthesizing and testing manganese gallium samples for spintronic applications.
Assistant Professor of Electrical Engineering Luqiao Liu is developing new magnetic materials known as antiferromagnets, such as manganese gallium samples, that can be operated at room temperature by reversing their electron spin and can serve as the basis for long lasting, spintronic computer memory. Materials Processing Center – Center for Materials Science and Engineering [MPC-CMSE] Summer Scholar Stephanie Bauman spent her internship making and testing these new materials.
Bauman, a University of South Florida physics major, says, “In our project we're working on the area of spintronics, anti-ferromagnetic devices that switch electron spin controlled by a current. I'm working with a lot of new equipment like the vibrating sample magnetometer and the sputterer to lay down thin films.”
“I’ve been working on a daily basis with Joe Finley, who is a graduate student here, and he’s been a explaining a lot of things to me,” Bauman notes. “It’s a very dense subject matter. And he does help me out a lot when we go to things like the X-ray diffraction room, and he shows me how the graphs can interpret how thick each layer of the thin layers of the devices are. He’s really helpful and easy to work with.”
During a visit to the lab, where she synthesizes these thin films with a special machine called a sputter deposition chamber, Bauman says, “I always go back to the checklist just to make sure I'm doing everything in the right order.” In order to take out a sample from the machine she has to follow a complicated set of steps, making sure its parts are correctly lined up and unhooking the sample holder in the main chamber. Because the chamber is pressurized, she must bring it back to everyday atmospheric pressure before taking it out. “Now that I can see that it disengaged, I go ahead and move it all the way back up,” she says. With the sample holder on a moveable arm, she can rotate it out.
|2017 MPC-CMSE Summer Scholar Stephanie Bauman holds a sample of manganese gallium, a new material known as an antiferromagnet, that can serve as the basis for long lasting, spintronic computer memory devices operated by reversing electron spin at room temperature. She interned this summer in the lab of Assistant Professor of Electrical Engineering Luqiao Liu. Photo, Denis Paiste, Materials Processing Center.|
The sample moves across a gear arm out of the main chamber into transfer chamber known as a load lock. “A very, very important part of this is to make sure you close the transfer valve again, otherwise you mess up the pressure in the main chamber,” she says. After double-checking the transfer valve is closed, she brings the load lock back to sea level pressure of 760 Torr. Then she takes out the sample holder.
“As you can see the sample is really tiny. It's half a centimeter by a half a centimeter, which is what we're working with right now,” Bauman says. As she loosens the screws on the arms holding the sample in place, she notes that she has to be careful not to scratch the sample with the arms. Once safely removed, she places the sample in a special holder labeled based on when each sample was made, which sample of the day it is and its thickness. That way, she notes, “we can refer back to that in our data so that we know what thickness levels that we’re testing.”
“Sometimes you end up playing tiddlywinks. I know that some younger people don't really know what that game is, but it's what it looks like when you push down on the arm, and the sample goes flying,” Bauman cautions.
Bauman then demonstrates how a new sample is loaded into the sputterer device. “Carefully tighten the screw, making sure not to torque it too much, then you move the other arm into place,” she says. Once both arms are tightened on the sample holder, she can put the sample into the load lock. “Very simple just make sure it's lined up correctly. It's also important to make sure the O-ring is clean, and so is the lid before you put it back on. That way there's a very good seal. So that's really it for the loading, and then you just turn the vacuum pumps back on and wait until it reaches the appropriate pressure and then load it into the main chamber.”
“I'm actually a non-traditional student, which means I'm a little bit older,” Bauman explains. “I have been in the military for 20 years, and I also had a civilian career for a long time in aviation contracts. I decided to go back to school for physics, and it's really been rewarding, especially this internship.”
Bauman’s internship is supported in part by NSF’s Materials Research Science and Engineering Centers program [grant DMR-14-19807]. Participants in the Research Experience for Undergraduates, co-sponsored by the Materials Processing Center and the Center for Materials Science and Engineering, presented their results at a poster session during the last week of the program. The program ran from June 15, 2017, to August 5, 2017, on the MIT campus in Cambridge, Mass.
– Denis Paiste, Materials Processing Center
Sept. 25, 2017
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|2017 MPC-CMSE Summer Scholar Stephanie Bauman presents her poster on her internship in the lab of Assistant Professor of Electrical Engineering Luqiao Liu making and testing new materials known as antiferromagnets, such as manganese gallium, that can serve as the basis for long lasting, spintronic computer memory devices operated by reversing their electron spin at room temperature. Photo, Denis Paiste, Materials Processing Center.|