Finite-momentum energy dynamics in a Kitaev magnet

Article

关键词: SPIN-LIQUID-STATE;    THERMAL-CONDUCTIVITY;    EXCITATIONS;    TRANSPORT;    HEAT;   

DOI  :  10.1103/PhysRevB.104.104424

来源: SCIE

【 摘 要 】

We study the energy-density dynamics at finite momentum of the two-dimensional Kitaev spin model on the honeycomb lattice. Due to fractionalization of magnetic moments, the energy relaxation occurs through mobile Majorana matter, coupled to a static Z(2) gauge field. At finite temperatures, the Z(2) flux excitations act as a thermally induced disorder, which strongly affects the energy dynamics. We show that sufficiently far above the flux proliferation temperature, but not yet in the high-temperature classical regime, disordered gauge configurations modify the coherent low-temperature energy-density dynamics into a form which is almost diffusive, with a diffusion kernel that is nearly momentum independent, but which remains retarded, primarily due to the presence of two distinct relaxation channels of particle-hole and particle-particle nature. Relations to the thermal conductivity are clarified. Our analysis is based on complementary calculations in the low-temperature homogeneous gauge configuration and a mean-field treatment of thermal gauge fluctuations, valid above the flux proliferation temperature.

【 授权许可】

Free