Luqiao Liu, MS ‘ 10, PhD ’12
Assistant Professor, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology
Magnetic Switching with Compensated Ferrimagnet and Topological Insulator
There has been great interest recently in using antiferromagnetic materials (AFM) as opposed to FM to store information. Compared with FM, AFM exhibit fast dynamics as well as robust protection against external magnetic fields, which can enable spintronic devices with fast speed and high density. However, the cancellation of total magnetic moment and the disappearance of magnetoresistance effect in AFM pose great difficulties on developing spintronic devices out of them. In this talk, I will discuss our recent study on rare earth based ferrimagnetic alloys which has antiferromagnetically coupled sublattices, net zero magnetic moment and electrically controllable magnetic state. Particularly, I will show that the inequality of the two sub-lattices provides finite electrical signal for convenient reading mechanism and spin orbit torque (SOT) induces magnetic switching allows for efficient writing mechanism. Moreover, I will also discuss our recent experiment work which integrates those compensated ferrimagnet with topological insulators, where the efficiency of spin orbit torque switching are significantly improved .
 J. Finley, L. Q. Liu, “Spin-Orbit-Torque Efficiency in Compensated Ferrimagnetic Cobalt-Terbium Alloys”, Physica Review, Applied, 6, 054001 (2016)
 J. Han, A. Richardella, S. S. Siddiqui, J. Finley, N. Samarth, and L. Liu. Room temperature spin-orbit torque switching induced by a topological insulator. Physical Review Letters, 119, 07702 (2017)
9:30 – 9:50 am
Vlad-Stefan Pribiag, MS ’06, PhD ’10
Assistant Professor, Department of Physics and Astronomy, University of Minnesota
Magnetism and superconductivity in MBE-grown complex oxide thin films
Complex oxide interfaces are a promising platform for studying a wide array of correlated electron phenomena in low-dimensions, including magnetism and superconductivity. The microscopic origin of these phenomena in oxide interfaces remains an open question. I will discuss our recent electronic transport studies on MBE-grownNdTiO3/SrTiO3 and SrTiO3 thin films down to 25 mK. The magnetoresistance of NdTiO3/SrTiO3 reveals steady-state signatures of local ferromagnetic order below ~4 Kelvin [arXiv1704.08828]. Moreover, the MR also shows transient hysteretic features with a characteristic timescale of ~100 seconds. I will discuss the importance of time-dependent measurements for distinguishing signatures of magnetism from other effects that can produce hysteretic MR in low-temperature experiments. I will conclude with our current efforts to explore superconductivity in NdTiO3/SrTiO3and doped SrTiO3 thin films.
9:50 – 10:10 am
Ilya Krivorotov, Post Doc 2002-2005
University of California, Irvine, Professor, Department of Physics & Astronomy and School of Physical Sciences
Condensation of Magnons by Spin Seebeck Current
10:10 – 10:30 am
Monica Plisch MS ’99, PhD ’01
American Physical Society, Director of Education and Diversity
Addressing the national shortage of qualified high school physics teachers
Fewer than half of all high school physics classrooms are led by a teacher with a degree in the subject, and physics is the number one shortage area for new teachers among all education fields. More than 70% of U.S. secondary education programs produced zero physics teachers in recent three-year period. The Physics Teacher Education Coalition (PhysTEC), a project of the American Physical Society and the American Association of Physics Teachers, has a mission to address the severe national shortage of qualified physics teachers. The project has established a coalition of more than 300 member institutions, including over 40% of all U.S. physics departments. PhysTEC has directly supported more than 40 colleges and universities to develop model programs that recruit and educate physics teachers. These supported sites have significantly increased the numbers of well-prepared physics teachers, and Comprehensive Sites that implement all PhysTEC Key Components have nearly tripled the number of program graduates. A study of physics majors showed that many students are interested in teaching, but have negative perceptions of the profession. Talking with students about teaching as a career option and providing accurate information about the profession encourages greater numbers to become teachers.
10:50 – 11:10 am
Elizabeth Carr, ’91, PhD ’94
Agilent, First-level Manager in R&D
Microarrays and Microfluidics for Life Science Analytical Instruments
11:10 – 11:30 am
Anuj Bhagwati ’91, MS ’94
Agilent, First-level Manager in R&D
Bob and Me: Changing My Major, Making My Management Style
11:30 – 11:50 am
Hans Hallen ’84, MS ’86, PhD ’91
North Carolina State University, Professor, Department of Physics
From electron tunneling to Raman spectroscopy: Bob’s lessons applied
As we meet to celebrate Bob’s 50 years here, and give several talks on here our careers have taken us, I thought it appropriate to cast mine n terms of Bob’s lessons, and shed some light onto how he has managed to keep such a productive and diverse research group all these years. In other words, I need to find a sensible reason why someone doing transport and tunneling in the Buhrman group ended up in biophysics, atmospherics and Raman spectroscopy, with a few other projects as well.
In the process I will share some interesting bits of science picked out along the way. Hot electron excitons are powerful, but stay in a grain, near-field Raman differs from far-field Raman, mainly due to the metal needed to confine the light, but there are also other inherently near-field effects, time (molecular) is important in Raman spectroscopy, understanding aerosol scattering means understanding the dielectric constant and how to get it, cell phone channels are dominated by interference (and diffraction) and are predictable, and resonance Raman near a phonon-allowed absorption can make a liquid act like a gas.
11:50 am – 12:10 pm
Stephen Russek MS ’86, PhD ’90
National Institute of Standards and Technology, Physicist, Magnetic Imaging Group
Spins in Humans
Proton spins form an excellent probe of properties within the living human body. Precessional frequencies and spin relaxation times can be sensitive to local chemical composition, water diffusion, blood flow, temperature, and neuronal activity. Quantitative MRI attempts to transition qualitative medical imaging into a precise mapping of multiple parameters within living patients so radiologists, oncologists, and neurologists do not have to guess about the meaning of medical images. Here, I present NIST work developing calibration artifacts (phantoms), standardized imaging protocols, and methods to validate in-vivo measurements. NIST has developed and commercialized a suite of MRI phantoms that are now being used in breast cancer clinical trials, traumatic brain injury studies, and the development of advanced imaging techniques such as MR Fingerprinting. Current efforts are focusing on biomimetic phantoms to assess the effect of concussion on neuronal tissue, development of calibration structures for magnetic susceptibility mapping in the brain, and imaging cell cultures during growth and differentiation in an MRI to correlate MRI accessible biomarkers with tissue properties.
1:30 – 1:50 pm
Ursula Gibson MS ’78, PhD ’82
Norwegian University of Science and Technology, Professor, Department of Physics
Oh, the places you’ll go
From the alma mater of Doctor Seuss to the four corners of the earth, this is the story of the times of, and the aftermath of, my degree at Cornell. My PhD was in optical materials, and that is the theme here, with a side trip into vortex magnetic states, and the bulk of the talk on semiconductor-core optical fibers, in which we are learning to control optical, crystalline and electronic properties under unusual thermodynamic conditions.
1:50 – 2:10 pm
Gösta Ehnholm, Post Doc 1979-1980
Aalto University, Visiting Scientist
A Postdoc in Bob’s Group, 1979
During the year of ’79 I worked as a senior post-doctoral associate in Bob’s group, on the recommendation of Bob Richardson, whom I learned to know during his stay at the low temperature laboratory of the Technical University of Helsinki. My topic of interest was the Josephson effect in superconductors which requires small structures to be seen: This fitted in nicely with the work on submicron structures that was started up by Bob and his group at Cornell. A practical application of the Josephson effect is for making SQUIDs, which are used for sensitive magnetometers e.g. for magnetic studies of the brain.
I found the work and interaction with Bob’s group highly enjoyable, both in the lab and outside, and I still remember many episodes from it. I continued working with SQUIDs after leaving Cornell during some periods, interacting with people that have formed a company (Neuromag) to commercialize it. One of them is now doing brain research at Harvard and asked me to join their group to build ultrasound transducers for this purpose. The human brain is an enigmatic object to study.
2:10 – 2:30 pm
Robert Bartynski ’80
Rutgers, The State University of New Jersey, Professor and Chair, Department of Physics and Astronomy
40 (of the 50) years of Bob Buhrman: Bob’s conscious and subconscious influence on the path from an A&EP undergrad to a physics & astronomy department chair
Mentor, role model, insightful sage, and many other phrases only understatement the spectrum of influences, both professional and personal, that Bob Buhrman has had on me, as well as many others that I’ve known throughout my career. I will recount a number of anecdotal examples of Bob’s grace, compassion, perspective and sense of humor that I’ve recalled and relied upon at many junctures and decision points in my career and in my life.