Synthesis and magnon thermal transport properties of spin ladder Sr₁₄Cu₂₄O₄₁ microstructures

Recent experiments on Sr₁₄Cu₂₄O₄₁ bulk single crystals have revealed a remarkable magnon thermal conductivity. Although Sr₁₄Cu₂₄O₄₁ crystals have been grown and studied extensively, there have been few reports on the synthesis and magnon thermal transport investigation of their microstructures. Here, we report the synthesis and thermal transport properties of Sr₁₄Cu₂₄O₄₁ microrods. These microrods synthesized by a co-precipitation 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 one-dimensional magnon transport along the ladder. Moreover, the thermal conductivity is enhanced after annealing as a result of reduced oxygen vacancies. These results provide useful insight on the transport of heat and quantum information based on quantum micro- and nanostructures.