Excitations and emergent quantum phenomena in a Kitaev honeycomb compound

by Prof. Arnab Banerjee (Perdue Univ.)

Monday 25 May 2020, 14:30 → 15:30 Europe/Berlin

Zoom Webinar

The Kitaev model on a honeycomb lattice predicts a special quantum spin liquid (QSL) ground state with excitations resembling Majorana Fermions and gauge flux excitations. These emergent features are exciting prospects to both basic physics and applications towards a lossless technology for quantum qubits.  In this talk, I will describe our recent range of experiments on the magnetic Mott insulator alpha-RuCl3 which has honeycomb layers held together with weak van-der-Waals interactions. Prominently, despite a long-range ordered ground state, our neutron scattering measurements reveal a continuum of fractionalized excitations resembling predictions from Majorana Fermions, confirming that the material is proximate to a QSL. In an 8T  magnetic field, the long-range order vanishes and the continuum becomes gapped, giving rise to hopes of a state where direct evidence of non-Abelian excitations has been measured. These include a half quantized fractional quantum Hall plateau in thermal Hall conductivity, and more recently, an intriguing Shubnikov de-Haas oscillations confirming a gapped spinon Fermi surface. I will end with future endeavors on this (class of) enigmatic magnetic material.