Ouassou Jabir Ali, Brataas Arne, Linder Jacob
Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
Phys Rev Lett. 2023 Aug 18;131(7):076003. doi: 10.1103/PhysRevLett.131.076003.
The ability of magnetic materials to modify superconductors is an active research area for possible applications in thermoelectricity, quantum sensing, and spintronics. We consider the fundamental properties of the Josephson effect in a class of magnetic materials that recently have attracted much attention: altermagnets. We show that despite having no net magnetization and a band structure qualitatively different from ferromagnets and from conventional antiferromagnets without spin-split bands, altermagnets induce 0-π oscillations. The decay length and oscillation period of the Josephson coupling are qualitatively different from ferromagnetic junctions and depend on the crystallographic orientation of the altermagnet. The Josephson effect in altermagnets thus serves a dual purpose: it acts as a signature that distinguishes altermagnetism from ferromagnetism and conventional antiferromagnetism and offers a way to control the supercurrent via flow direction anisotropy.
磁性材料对超导体的改性能力是热电、量子传感和自旋电子学等潜在应用领域的一个活跃研究方向。我们考虑了一类最近备受关注的磁性材料——交替磁体中约瑟夫森效应的基本特性。我们表明，尽管交替磁体没有净磁化，且其能带结构在定性上不同于铁磁体以及没有自旋分裂能带的传统反铁磁体，但交替磁体仍会诱发0-π振荡。约瑟夫森耦合的衰减长度和振荡周期在定性上不同于铁磁结，且取决于交替磁体的晶体取向。因此，交替磁体中的约瑟夫森效应具有双重作用：它作为一种特征，将交替磁性与铁磁性和传统反铁磁性区分开来，并提供了一种通过流方向各向异性来控制超电流的方法。
