近日，美国布鲁克海文国家实验室Valentina Bisogni团队实现了用共振非弹性x射线散射观察微分自旋电流。相关论文于2025年9月10日发表在《自然》杂志上。

在小型磁性器件中控制自旋电流，即自旋角动量的流动，是自旋电子学的主要目标，也是未来节能信息技术的主要竞争者。纯自旋电流从未被直接测量过，因为相关的杂散场和/或非平衡自旋相关分布函数中的位移对于针对电荷输运优化的传统实验检测方法来说太小了。

研究组报告了共振非弹性x射线散射（RIXS）可以通过测量磁振子携带的自旋电流来弥补这一差距，磁振子是磁阶自旋波激发的量子，在磁绝缘体存在温度梯度的情况下。这有望实现，因为在非平衡条件下，动量和能量分辨的RIXS强度对磁振子分布的微小变化很敏感。研究组在弛豫时间近似中引入玻尔兹曼方程来提取输运参数，如有限动量下的磁振子寿命，这是实现磁振子自旋电子学所必需的。

附：英文原文

Title: Observing differential spin currents by resonant inelastic X-ray scattering

Author: Gu, Yanhong, Barker, Joseph, Li, Jiemin, Kikkawa, Takashi, Camino, Fernando, Kisslinger, Kim, Sinsheimer, John, Lienhard, Lukas, Bauer, Jackson J., Ross, Caroline A., Basov, Dmitri N., Saitoh, Eiji, Pelliciari, Jonathan, Bauer, Gerrit E. W., Bisogni, Valentina

Issue&Volume: 2025-09-10

Abstract: Controlling spin currents, that is, the flow of spin angular momentum, in small magnetic devices, is the principal objective of spin electronics, a main contender for future energy-efficient information technologies1,2. A pure spin current has never been measured directly because the associated electric stray fields and/or shifts in the non-equilibrium spin-dependent distribution functions are too small for conventional experimental detection methods optimized for charge transport3,4. Here we report that resonant inelastic X-ray scattering (RIXS) can bridge this gap by measuring the spin current carried by magnons—the quanta of the spin wave excitations of the magnetic order—in the presence of temperature gradients across a magnetic insulator. This is possible due to the sensitivity of the momentum- and energy-resolved RIXS intensity to minute changes in the magnon distribution under non-equilibrium conditions. We use the Boltzmann equation in the relaxation time approximation to extract transport parameters, such as the magnon lifetime at finite momentum, essential for the realization of magnon spintronics.

DOI: 10.1038/s41586-025-09488-9

Source: https://www.nature.com/articles/s41586-025-09488-9