Finazzi Marco, Bottegoni Federico, Zucchetti Carlo, Isella Giovanni, Ciccacci Franco
LNESS-Physics Department, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
Sci Rep. 2018 Nov 20;8(1):17108. doi: 10.1038/s41598-018-35336-0.
Spin transport phenomena have been shown to be highly enhanced when the temperature approaches the Curie point of the material sustaining a spin flow. Here we propose a simple - yet unifying - explanation for such enhancements, based on a random-phase model accounting for the spin fluctuations within a ferromagnetic material in the paramagnetic phase. We show that pure spin currents carried by conduction electrons injected into a paramagnetic lattice of mutually interacting localized magnetic moments can be enhanced close to the Curie temperature by the exchange interaction between the lattice sites and the non vanishing spin density associated with the spin current. The latter partially aligns the magnetic moments of the lattice, generating a flow of paramagnons that contribute to the total spin current, resulting in an enhancement that can be as large as tenfold.
当温度接近维持自旋流的材料的居里点时，自旋输运现象已被证明会显著增强。在此，我们基于一个随机相位模型，针对此类增强现象提出了一种简单却统一的解释，该模型考虑了顺磁相中铁磁材料内的自旋涨落。我们表明，注入到相互作用的局域磁矩的顺磁晶格中的传导电子所携带的纯自旋电流，在接近居里温度时，会通过晶格位点之间的交换相互作用以及与自旋电流相关的非零自旋密度而增强。后者会使晶格的磁矩部分对齐，产生顺磁子流，该顺磁子流对总自旋电流有贡献，从而导致增强幅度可达十倍之多。
