In this Issue:

We are delighted to announce that Professor Hao Zeng received the UB Exceptional Scholar: Sustained Achievement Award 2022. In January, we welcomed Dr. Changjiang Liu (tenure-track Assistant Professor) and in August, we welcomed Dr. Herbert Fotso (tenure-track Associate Professor). Dr. Liu’s research interests are in experimental condensed matter physics in the field of synthesis of quantum materials (superconductivity, spintronics) and Dr. Fotso’s research interests are in theoretical/computational condensed matter physics (quantum information processing, correlated quantum systems). SUNY Distinguished Professor Eckhard Krotscheck retired earlier this year after a stellar research and teaching career spanning 50 years. We thank Eckhard for his contributions to the department and the physics community, please join me in wishing him all the best in retirement.

As many of you know, our department has long been known for students, staff and faculty with diverse ethnic, gender, racial identities and has been a welcome home for members from different cultures and nationalities. Hence it is not surprising that the physics community felt significantly troubled by recent worldwide events and the department has established an Equity, Diversity and Inclusion (EDI) committee last year. We have initiated activities during the Black History Month and also participated in the inaugural Visiting Future Faculty Program (VITAL), an exciting and rewarding four-day program that brings outstanding doctoral scholars from all disciplines to the University at Buffalo. Margaret Ikape, from the University of Toronto, visited the department as a VITAL scholar in April 2022. VITAL program seeks to contribute to the growth of faculty from traditionally underrepresented populations in the United States, particularly from Indigenous, African American/Black, and Hispanic/Latinx backgrounds. I am committed to continue our activities and that the department will continue to participate and contribute to the efforts at UB and wider community towards equity, diversity and inclusion.

In 2022, we were excited to resume both of our popular public lecture series (Ta-You Wu Memorial lecture and Rustgi Memorial lecture) after a two-year break. Nobel Laureate Professor Stanley Whittingham visited the department to present the seventh Ta-You Wu Memorial lecture on lithium batteries on April 29, 2022. The campus came alive to welcome the Nobel Laureate and enjoyed the personal interactions and his lecture.  Professor Hideo Hosono (Tokyo Institute of Technology, Japan) presented the eighth Ta-You Wu Memorial lecture on October 14. Professor Hosono is a pioneer in developing transparent oxide semiconductors that are widely used in displays of televisions, mobile devices, etc.

We are grateful to Professor Emeritus Bruce D. McCombe who was instrumental in creating an endowed fund, the Jiping Cheng Graduate Student Achievement Award, in memory of our alumnus, Dr. Jiping Cheng (PhD ’89), to be used for the purpose of supporting graduate student in physics. We thank Dr. Cheng’s wife, Dr. Wang, and friends who generously donated towards this fund.

Post-pandemic, we strive to engage with our alumni in better ways than before: I visited Portland, OR in May to meet with our department alumni working in Intel Inc. and other high-tech industries in that region. During the Fall semester, we invited two of our alumni (Dr. Alex Kitt, Director of Data Science, EWI and Dr. Luke Lyle, Research Assistant Professor, Penn State) to present their research and work and to provide mentoring and networking opportunities for our current students. We take immense pride in the success and careers of our students and alumni. We would love to hear about your work and life and look forward to an opportunity to host you here in Buffalo!

Stay in touch, be safe, stay healthy and I am sure we will have more exciting stories to share in the future.

Best regards,
Sambandamurthy Ganapathy

Chair and Professor of Physics

By Hao Zeng, PhD and Mengying Bian, PhD

With just the right number and strength of chemical bonds, Goldilocks epitaxy allows high quality crystalline thin films to be grown on any substrate. Growing oriented thin films on a single crystal substrate called epitaxy is a ubiquitous technology in the semiconductor industry. Conventional epitaxial growth relies on strong covalent bonding between a thin film and a substrate to fix the crystalline orientation. The stringent lattice matching requirement means that only a limited number of materials can be epitaxially grown with adequate quality. Further, interfacial strain due to the lattice mismatch between the two materials inevitably leads to defect formation, degrading device performance. Van der Waals epitaxy developed in the 1980’s circumvents such problems. However, the weak interactions result in misorientations of the grown films. The discovery of a new regime of thin film epitaxy promises to address these limitations.    In a recent paper (Advanced Materials, 34, 2200117, 2022), the Zeng group discussed a new technique to grow epitaxial thin films on a van der Waals template, taking advantage of a special type of chemical bond called dative bond formed at the interface. Dative bonds with the right number and strength fix the crystalline orientation without lattice matching, while still allow strain relaxation to minimize interfacial defects.

Dative epitaxy could be useful for the semiconductor industry, by enabling technologically important compound semiconductors be epitaxially grown on complementary metal-oxide-semiconductor (CMOS) compatible substrates without lattice matching constraints, and with crystal qualities rivaling or exceeding those using conventional epitaxial techniques. UB has filed a provisional patent application for dative epitaxy methods, and is looking to expand on this research through collaboration with industry and research partners. The work also provides opportunities to explore interesting fundamental physics originating from the moiré superlattices formed by two atomically thin layers with large lattice mismatch, grown by dative epitaxy.

The experimental work in Zeng’s lab was led by former postdoc Mengying Bian with participation from graduate student Chang Huai and undergraduate student Austin Marga. Austin won a prestigious National Science Foundation Graduate Research Fellowship and is now a graduate student at Northwestern University. Dr. Bian is now an associate professor at the Beijing University of Technology.

Changjiang Liu, PhD, joined the Department of Physics as Assistant Professor in the spring of 2022. He received his PhD in physics from the University of Minnesota, where he was focused on the study of spin transport in semiconductors. In his PhD thesis, he demonstrated how spin accumulations in semiconductors can be effectively detected using ferromagnetic resonance, which also allows for the measurement of short spin lifetimes below 100 picoseconds. Afterwards, he continued his research career as a postdoc at Argonne National Laboratory, where he used molecular beam epitaxy to grow quantum materials and investigated their emergent phenomena. He found that short-range magnetic ordering in frustrated magnetic systems can be detected using thermal excitations of magnons which is also known as the spin Seebeck effect. He observed signatures of antiferromagnetic quantum critical point in high-purity LaNiO₃. He discovered two-dimensional superconductivity at interfaces of KTaO₃ with other oxide insulators. The interfacial superconductivity of KTaO₃ oxide system is tunable and with superconducting transition temperatures significantly higher than the existing oxide interfaces based on SrTiO₃. He also demonstrated how magnon spin current can be electrically controlled in an antiferromagnet by using a magnetoelectric coupling. At UB, Dr. Liu will continue to use molecular beam epitaxy to synthesize quantum materials and investigate the charge/spin transport, magnetic, structural and optical properties of those materials. He anticipates that much more exciting physics can be uncovered in newly synthesized quantum materials.

Herbert F. Fotso, PhD, joined the Department of Physics as Associate Professor in the fall of 2022. He received his PhD in 2011 at Louisiana State University. In his thesis, he developed petascale numerical solutions for diagrammatic methods addressing strongly correlated quantum systems. After completing his thesis, he had postdoctoral fellowships at Georgetown University and at the Department of Energy (DOE) Ames Laboratory in Ames, Iowa. He was a faculty member with the Department of Physics at the University at Albany, SUNY from September 2016 until the summer of 2022. In his research, he studies the non-equilibrium dynamics of many-particle quantum systems with an emphasis on light-matter interactions that are relevant for Quantum Information Processing. He also studies the non-equilibrium dynamics of strongly correlated systems with the goal of understanding novel properties that arise away from equilibrium in these systems. These studies also aim to benchmark experimental efforts that study non-equilibrium processes in relevant materials both from the point of view of time-dependent spectroscopy experiments, and from the point of view of ultracold atomic gases in optical lattices to emulate various lattice models. In addition to applying a combination of analytical and computational approaches to problems across many subfields of Physics including AMO, Condensed Matter Physics, and Quantum Information Science, Herbert enjoys working with students and discussing science with broad audiences.

Margaret Ikape is a PhD candidate in the Dunlap Institute for Astronomy and Astrophysics, David A Dunlap Department of Astronomy and Astrophysics, University of Toronto. She was born in Nigeria, where she received her undergraduate degree in Physics and Astronomy. She completed a Masters degree in the African Institute for Mathematical Sciences, AIMS, Cameroon before beginning graduate studies in Toronto. Her interest in astronomy started at a very young age and that interest has been sustained by the numerous unknowns in the universe. Her current work tries to understand the nature of the first stars using simulated data. Ikape presented a department colloquium titled “Probing the Epoch of Reionization with the Simons Observatory” on March 31, 2022. UB’s inaugural class of 2022 VITAL scholars was featured in a UBNow article.

The Visiting Future Faculty Program (VITAL) is an exciting and rewarding four-day program that brings outstanding doctoral scholars from all disciplines to the University at Buffalo. VITAL seeks to contribute to the growth of faculty from traditionally underrepresented populations in the United States, particularly from Indigenous, African American/Black, and Hispanic/Latinx backgrounds. VITAL scholars have the opportunity to present their work, engage with UB faculty and students, meet other scholars in the program, and experience the region’s many offerings. Doctoral scholars in physics who are interested to be part of this program, please reach out to us!

This prestigious prize is awarded annually “to recognize and encourage outstanding theoretical or experimental contributions to condensed matter physics.”

The co-recipients’ early work concerned the effects of spin-orbit interaction on the band structure near the Brillouin Zone center of zinc blende and wurtzite semiconductors, whose crystal lattices lack inversion symmetry. Their results guided our understanding of anisotropies in important electronic quantities in the otherwise nearly spherically symmetric conduction band of these semiconductor crystals.  More recently, their results have been employed in schemes to manipulate and control electron spins. Bychkov and Rashba showed that Rashba’s early results could be taken over to quasi-two-dimensional carriers in materials that possess inversion symmetry with an asymmetry introduced by external means.  This led to a variety of potential applications of different materials and structures, the iconic application being the spin transistor. Many approaches for spintronics or quantum information technologies have made use of these results for device structures that control spins via electric fields. The importance of this work has been tremendous, not only as the seminal work in the whole field of spin-orbit effects in semiconductors, but also in stimulating new physics and applications. It is still having important impact in spintronics, nanostructures and quantum computing, as well as in several emerging areas of research and applications, e.g., topological insulators, graphene, and Majorana fermions.

Interestingly (especially to me), Rashba’s theoretical work had a strong effect on my career.  Two colleagues and I were inspired by Rashba’s early papers to investigate the predicted combined (cyclotron plus spin)-resonance in n-type InSb.  We published initial results in 1967, and I met Rashba at the 1968 International Conference on the Physics of Semiconductors in Moscow.  He was pleased that we had been able to observe the combined resonance (communication was slower in those days.), and he encouraged me to continue our work. We met again at the joint US-Soviet Symposium in Moscow in 1988, during which the US delegation visited Chernogolovka (the first time for US scientists).  We did not meet again until after he had moved to the University of Utah and had survived a serious illness. At that time, when the “spintronics” effort was flowering, a group of us wrote a successful consortium proposal to DARPA.  We appointed Rashba to a Research Professorship in Physics. He was a great collaborator, very generous and helpful to me and other colleagues and to several of our students.  He was a delightful presence in the Department of Physics when he visited.  He gladly spoke with students, as well as with his collaborators on the faculty, on those occasions. All of us benefitted greatly from his contact and interactions.