Kuzmanović M, Wu B Y, Weideneder M, Quay C H L, Aprili M
Laboratoire de Physique des Solides (CNRS UMR 8502), Université Paris-Saclay, 91405, Orsay, France.
Graduate Institute of Applied Physics, National Taiwan University, Taipei, 10617, Taiwan.
Nat Commun. 2020 Aug 28;11(1):4336. doi: 10.1038/s41467-020-18161-w.
In ferromagnetic materials, spin up and down electrons can carry different heat currents. This spin-dependent energy excitation mode ('spin energy mode') occurs only when spin up and down energy distribution functions are different. In superconductors, heat is carried by quasiparticle excitations and the spin energy mode can be excited by spin-polarised current injection. In the presence of a finite Zeeman magnetic field, the spin energy mode surprisingly leads to a charge imbalance (different numbers of hole- and electron-like quasiparticles) at the superconducting gap edge. By performing spin-resolved spectroscopy of the out-of-equilibrium quasiparticle populations in a mescoscopic superconductor, we reveal that their distribution functions are non-Fermi-Dirac. In addition, our spectroscopic technique allows us to observe a charge imbalance, localised in energy to the gap edge and thus unambiguously identify the spin energy mode. Our results agree well with theory and shed light on energy transport in superconducting spintronics.
在铁磁材料中，自旋向上和向下的电子可以携带不同的热流。这种自旋相关的能量激发模式（“自旋能量模式”）仅在自旋向上和向下的能量分布函数不同时才会出现。在超导体中，热量由准粒子激发携带，并且自旋能量模式可以通过自旋极化电流注入来激发。在存在有限塞曼磁场的情况下，自旋能量模式令人惊讶地在超导能隙边缘导致电荷不平衡（不同数量的类空穴和类电子准粒子）。通过对介观超导体中处于非平衡态的准粒子群体进行自旋分辨光谱研究，我们发现它们的分布函数不是费米 - 狄拉克分布。此外，我们的光谱技术使我们能够观察到一种电荷不平衡，其能量局域在能隙边缘，从而明确地识别出自旋能量模式。我们的结果与理论非常吻合，并为超导自旋电子学中的能量传输提供了新的见解。
