Synthesis and Magnon Thermal Transport Properties of Spin Ladder Sr14Cu24O41 Microstructures

Abstract

The spin ladder compound (Sr,Ca,La)(14)Cu24O41 exhibits an incommensurate layered structure with strong antiferromagnetic coupling. Besides intriguing superconducting behavior, recent experiments on bulk Sr14Cu24O41 single crystals have revealed a remarkable magnon thermal conductivity, which is the largest above 100 K among all known quantum magnets. Although bulk (Sr,Ca,La)(14)Cu24O41 crystals have been synthesized and studied extensively, there have been few reports on the synthesis and magnon thermal transport investigation of their microstructures. Here, the synthesis and thermal transport properties of Sr14Cu24O41 microrods are reported. Electron microscopy studies indicate that these microrods synthesized by a coprecipitation method are single crystals grown preferentially along the ladder axis. Based on a four-probe thermal transport measurement, the thermal conductivity of the microrods reveals appreciable magnon transport in the microstructures. According to a kinetic model analysis, magnon transport in the microrods is suppressed mainly by increased point defect scattering compared to the bulk crystals, whereas surface scattering is negligible for anisotropic 1D magnon transport along the ladder. Moreover, the thermal conductivity is enhanced after annealing as a result of reduced oxygen vacancies. These results help to build the foundation for future heterogeneous integration of magnetic microstructures in microscale devices for the transport of energy and quantum information.