Materials Science Research Lecture

***Refreshments at 3:45pm in Noyes lobby

Abstract:

Alexei Kitaev proposed the existence of a quantum spin liquid state in frustrated honeycomb magnets that exhibit gauge fluxes and Majorana fermions which hybridize into non-abelian sectors in a magnetic field promising a viable avenue towards decoherence-resistant solid-state quantum logic. Spin-1/2 Honeycomb magnet alpha-RuCl3 shows strong bond-directional Kitaev interactions with a low antiferromagnetic ordered moment at zero field. At above 7.3 T in-plane magnetic field, this order is suppressed, revealing a quantum spin liquid state that exhibits a spinon continuum and, arguably, a ½-quantized thermal hall plateau arising from Majorana Fermions by some groups. In this talk, we discuss our recent inelastic neutron data taken between 8 – 14 T to shed light on this enigmatic state. We reveal the evolution of the spinon continuum and its condensation into spinon and magnon bound states at high fields. We further reveal the behavior of the spin gap in a restricted regime of the Brillouin zone and discuss its implications. Finally, I will end with a discussion of electrical measurements on metal-RuCl3 devices, which show evidence of characteristic energy scales and transitions relevant to the thermal transport measurements and future spin-liquid-based tunnel junctions.

More about the Speaker:

Arnab Banerjee works on experimental measurements and quantum computations that could reveal new, exotic, states of magnetic matter. He received his PhD with Prof. Thomas Rosenbaum at the University of Chicago on high-pressure techniques in 2013, followed by a post-doctoral fellowship at Oak Ridge National Laboratory (ORNL), where he eventually became a staff scientist working on quantum magnetism. He joined Purdue University, West Lafayette, in 2020 where he is an Assistant Professor of Physics and Astronomy. His work on Kitaev quantum magnetism was adjudged top 100 discoveries by Discover Magazine in 2017 and earned him several accolades such as the MRS Postdoctoral award. His current research is funded by DOE National Quantum Initiative, DOE-BES as well as NSF.