Using Resonant Inelastic X-ray Scattering to study quasiparticle fractionalization in quasi-one-dimensional cuprates

Condensed Matter Seminars

Speaker: Steve Johnston, University of Tennessee
Date & Time: Fri, 2018-01-05 14:00 - 15:00
Location: AMPEL #311
Local Contact: Mona Berciu
Intended Audience:

One-dimensional (1D) magnetic materials have attracted significant interest as a platform for studying phenomena such as quasiparticle fractionalization and quantum criticality. The spin-1/2 1D Heisenberg antiferromagnet is a vital system;  its elementary excitations are chargeless spin-1/2 quasiparticles called spinons that are created in pairs. While inelastic neutron scattering (INS) experiments observe the two-spinon continuum regularly, the presence of four-spinon excitations has only been inferred from discrepancies between measured and calculated spectral weights in phase space overlapping with the two-spinon continuum. Here, I will show that resonant inelastic x-ray scattering (RIXS) is capable of accessing the four-spinon excitations directly and well separated from the two-spinon continuum. Our results provide the first direct measurement of four-spinon excitations, which is made possible by the fundamentally different correlation functions probed by RIXS compared to INS. I will also show theoretical predictions for the observation of multi-spinon and holon excitations in the doped systems. This advance holds great promise as a tool in the search for novel quantum states, in particular, quantum spin liquids.