Description:

Abstract: . Nonmagnetic materials with unidirectional spin-momentum locking, or persistent spin textures (PST), have been shown to exhibit spin transport properties useful for future microelectronic devices. The potential for long spin lifetimes available to PSTs has garnered broad interest since being first theoretically proposed [Phys. Rev. Lett. 97, 236601 (2006)] and subsequently demonstrated in experiment [Nature 458, 610-613 (2009)]. In the last 15 years, two main routes have been theoretically proposed to realize PSTs: (1) Engineering quantum well structures and (2) exploiting nonsymmorphic symmetries to introduce topological protection. Few three-dimensional materials are known to host PSTs owing to crystal symmetry and chemical requirements and there are even fewer examples demonstrated experimentally. Among those available, the calculated or measured persistent spin helix (PSH) is very short, motivating searches for new mechanisms and materials. Here, I will discuss our latest group-theoretical and computational approaches for identifying and designing materials with high-quality PSTs. I will explain how we arrive at electronic structure-based descriptors to assess the quality of the PSTs. I will also show how monoclinic and trigonal crystal systems, which are ubiquitous among known ferroelectrics, can host high-quality PSTs either from an odd number of mirror (symmorphic) symmetries or through an accidental modality based on enhanced Rashba anisotropy. Our work provides a path to pursue persistent-spin-helix design in quantum materials exhibiting diverse chemistries in various dimensionalities and large Rashba coefficients.

Speaker: James Rondinelli, Professor of Materials Science and Engineering, Northwestern University

Rondinelli is the Walter Dill Scott Professor at Northwestern University (NU) in the Materials Science and Engineering (MSE) Department and Applied Physics Program, where he leads the Materials Theory and Design Group. He serves as Co-Director of the Predictive Science and Engineering Design (PS&ED) Program and Associate Director of the NSF Materials Research Science and Engineering Center (MRSEC) at NU. His research interests are in electronic structure theory and first-principles design of functional inorganic materials using picoscale structure-property relationships. He is a 2018 Kavli Frontiers of Science Fellow and the 2017 Materials Research Society (MRS) Outstanding Young Investigator. In 2016 he received a Sloan Research Fellowship in Physics, the Presidential Early Career Award for Scientists and Engineers (PECASE), and the 3M Non-Tenured Faculty Award. Additional honors include a NSF-CAREER Award (2015), DARPA Young Faculty Award (2012), and ARO Young Investigator Program (YIP) award (2012). He received the 2014 Ross Coffin Purdy Award from the American Ceramic Society and was named an Emerging Young Investigator by the Royal Society of Chemistry (J. Mater. Chem. C, 2016) and the American Chemical Society (Chem. Mater., 2014). Rondinelli has (co)-authored more than 225 peer-reviewed publications (h-index=63, 15670 citations) and holds 2 patents. He is a member of the APS, MRS, ACS, TMS, ACerS, and ASEE, and has organized multiple symposia for these societies on the physics and chemistry of transition metal compounds. He serves as an editorial board member of the Journal of Physics: Condensed Matter (2017-) and npj Computational Materials (2015-). Rondinelli is also a member of the MRS Academic Affairs Committee (2015-), former Member-at-Large for the Division of Materials Physics (DMP) of the APS (2018-21), and former Chair of the Argonne Center for Nanoscale Materials (CNM) Users’ Executive Committee (2016-19). He currently serves as Vice-Chair for the DMP of the APS. He received a B.S. in MSE from NU (2006) and a Ph.D. in Materials from the University of California, Santa Barbara (2010). From 2010-2011, he was the Joseph Katz Named Fellow in the X-Ray Science Division at Argonne National Laboratory. Prior to joining NU, he was an assistant professor at Drexel University (2011-14).

Host: Pallab Goswami