非平衡磁振子工程实现显著的热输运调控
Non-equilibrium Magnon Engineering Enabling Significant Thermal Transport Modulation
AI总结：
本文提出磁振子热输运工程，通过调控非平衡自旋电流的空间分布，揭示了室温下磁振子对铁磁金属热传导的显著贡献，颠覆了传统认知，为主动热管理提供了新原理和方法。
摘要：
热导率是表征固体中热输运的基本参数，通常由电子和声子输运决定。尽管包括电导率和热电转换系数在内的其他输运性质具有材料特异性，但已知热导率可以通过声子工程技术进行人工调控。在此，我们展示了人工调控固体中热传导的另一种方式：磁振子热输运工程。使用铁磁金属/绝缘体结系统进行的时域热反射测量表明，铁磁金属的热导率和界面热导会根据非平衡自旋电流的空间分布发生显著变化。通过改变自旋电流的边界条件对热输运性质进行的系统测量表明，观察到的热输运调控源于磁振子。这一观察揭示了，即使在室温下的铁磁金属中，磁振子也对热传导有显著贡献，这颠覆了传统观点，即除了在低温下，金属中由磁振子介导的热导率非常小。磁振子热输运工程为主动热管理提供了新的原理和方法。
英文摘要：
Thermal conductivity, a fundamental parameter characterizing thermal transport in solids, is typically determined by electron and phonon transport. Although other transport properties including electrical conductivity and thermoelectric conversion coefficients have material-specific values, it is known that thermal conductivity can be modulated artificially via phonon engineering techniques. Here, we demonstrate another way of artificially modulating the heat conduction in solids: magnonic thermal transport engineering. The time-domain thermoreflectance measurements using ferromagnetic metal/insulator junction systems reveal that the thermal conductivity of the ferromagnetic metals and interfacial thermal conductance vary significantly depending on the spatial distribution of nonequilibrium spin currents. Systematic measurements of the thermal transport properties with changing the boundary conditions for spin currents show that the observed thermal transport modulation stems from magnon origin. This observation unveils that magnons significantly contribute to the heat conduction even in ferromagnetic metals at room temperature, upsetting the conventional wisdom that the thermal conductivity mediated by magnons is very small in metals except at low temperatures. The magnonic thermal transport engineering offers a new principle and method for active thermal management.
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