Speaker: Wen-Han Kao, PhD graduate student in Physics at Univ of Minnesota
Abstract: One of the long-standing open questions that recently attracted much attention is understanding how a quantum spin liquid (QSL) state responds to various forms of structural disorder that are inevitable in real materials. In the candidate compounds of the Kitaev spin liquid (KSL) system, it has been noted that quenched disorder plays a role in suppressing the long-range magnetic order but also makes the low-energy excitations puzzling. In my talk, I will introduce how the presence of vacancies and bond randomness modifies the density of states of Majorana fermion, which is one kind of fractionalized excitation of KSL. In the site-diluted model, the pileup of low-energy states leads to divergent specific heat, and the flux-sector crossover under magnetic fields provides an explanation for the puzzling experimental findings of a strong candidate material H3LiIr2O6. We also explored how the fractionalized degrees of freedom renormalize in the strong-disorder limit of bond randomness. Namely, we applied the strong-disorder renormalization group (SDRG) on the KSL system and found that strong-disorder criticality can appear differently on distinct fractionalized excitations. This points out further inquiries about the quenched disorder effects in frustrated magnetism.