Theory for shift current of bosons: Photogalvanic spin current in ferrimagnetic and antiferromagnetic insulators
Theory for shift current of bosons: Photogalvanic spin current in ferrimagnetic and antiferromagnetic insulators
复制标题
玻色子移动电流理论：亚铁磁和反铁磁绝缘体中的光电自旋电流
DOI：
10.1103/physrevb.100.224411
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发表时间：
2019
影响因子：
3.7
通讯作者：
Sato Masahiro
中科院分区：
文献类型：
--
作者：
Ishizuka Hiroaki;Sato Masahiro
我们从理论上研究了有序反铁磁和铁磁绝缘体中直流自旋电流（即自旋电流太阳能电池）的光学产生，这是受到最近对非中心对称量子自旋链中激光驱动自旋电流的研究的启发[H]。伊什祖卡和M.佐藤，物理学家。[j].科学通报，2012,(5):951 - 951。利用磁振子的非线性响应理论，我们分析了线性极化电磁波（通常是太赫兹或千兆赫波）产生的直流自旋电流。以非中心对称双亚晶格磁体为例，在不存在热激磁子的情况下，我们发现了有限的直流自旋电流电导率；这与自旋子自旋电流的情况相反，在自旋电流中，费米简并自旋子的光学跃迁起着重要作用。我们发现直流自旋电流的电导率对吉尔伯特阻尼不敏感，即它可以被视为由玻色子粒子（磁振子）携带的移位电流。我们的估计表明，电场强度为v /cm足以产生可观测的自旋电流。我们的理论表明，线极化电磁波在非中心对称磁绝缘体中一般产生直流自旋电流。
We theoretically study the optical generation of dc spin current (i.e., a spin-current solar cell) in ordered antiferromagnetic and ferrimagnetic insulators, motivated by a recent study on the laser-driven spinon spin current in noncentrosymmetric quantum spin chains [H. Ishizuka and M. Sato, Phys. Rev. Lett. 122, 197702 (2019)PRLTAO0031-900710.1103/PhysRevLett.122.197702]. Using a nonlinear response theory for magnons, we analyze the dc spin current generated by a linearly polarized electromagnetic wave (typically, terahertz or gigahertz waves). Considering noncentrosymmetric two-sublattice magnets as an example, we find a finite dc spin-current conductivity at, where no thermally excited magnons exist; this is in contrast to the case of the spinon spin current, in which the optical transition of the Fermi degenerate spinons plays an essential role. We find that the dc spin-current conductivity is insensitive to the Gilbert damping, i.e., it may be viewed as a shift current carried by bosonic particles (magnons). Our estimate shows that an electric-field intensity ofV/cm is sufficient for an observable spin current. Our theory indicates that the linearly polarized electromagnetic wave generally produces a dc spin current in noncentrosymmetric magnetic insulators.