Majorana fermions bound to line defects in Kitaev spin liquids

Abstract: The field-induced Kitaev spin liquid is a strongly correlated topological phase which may have been realized in the layered material alpha-RuCl3. It is characterized by the presence of gapped non-Abelian anyon excitations in the bulk and gapless chiral Majorana modes at the edges. In this talk I will show that gapless one-dimensional modes can also survive in the bulk of the Kitaev spin liquid when they are bound to line defects at which the exchange interaction falls below a critical value. Treating the weak interaction at the line defect within a mean-field approximation, we determine the critical interaction strength as a function of the external magnetic field. In the gapless regime, we use the low-energy effective field theory to calculate the spin-lattice relaxation rate for a spin near the defect. I will also discuss the relevance of these results to nuclear magnetic resonance experiments that claimed to have observed gapless excitations in the putative spin liquid phase of alpha-RuCl3.

Physics

Audience: general audience

Virtual Seminar of the International Institute of Physics

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