Discovering momentum-dependent magnon spin texture in insulating antiferromagnets: Role of the Kitaev interaction
Discovering momentum-dependent magnon spin texture in insulating antiferromagnets: Role of the Kitaev interaction
复制标题
DOI：
10.1103/physrevb.100.174402
复制
发表时间：
2019-11-01
影响因子：
3.7
通讯作者：
Hotta, Chisa
中科院分区：
文献类型：
--
作者：
Kawano, Masataka;Hotta, Chisa
我们从理论上证明，基塔耶夫相互作用在基塔耶夫-海森堡-伽马模型中发现的反铁磁绝缘体的激发光谱中产生了一类新型的自旋织构。在传导电子系统中，沿着费米表面存在一系列由 Rashba 和 Dresselhaus 自旋轨道耦合引起的涡旋类型的自旋纹理。这种自旋结构在磁绝缘体中很少发现，因为没有系统的方法来使用磁场或空间不对称交换耦合来控制其称为磁振子的准粒子的动力学。在这里，我们提出了一个通用框架来探索任意绝缘反铁磁体中的这种自旋纹理。我们引入了一种分析方法，可将任何复杂的哈密顿量转换为基于赝自旋自由度的简单表示，该自由度与动量相关的虚拟“塞曼场”耦合。布洛赫球上赝自旋的方向描述了两个磁性亚晶格对磁振子携带的自旋矩的贡献程度。在那里，“塞曼场”决定了赝自旋的方向，从而成为自旋纹理的控制参数，由原始模型参数明确描述。该框架使我们能够阐明基塔耶夫相互作用中未发现的方面，并进一步提供了一种工具来轻松设计或探索具有有趣磁性的材料。由于这些自旋织构可以成为纯自旋电流的来源，因此Kitaev材料A(2)PrO(3)（A = Li，Na）将成为节能自旋电子器件的潜在平台。
We theoretically show that the Kitaev interaction generates a novel class of spin texture in the excitation spectrum of the antiferromagnetic insulator found in the Kitaev-Heisenberg-Gamma model. In conducting electronic systems, there is a series of vortex type of spin texture along the Fermi surface induced by Rashba and Dresselhaus spin-orbit couplings. Such spin textures are rarely found in magnetic insulators since there had been no systematic ways to control the kinetics of its quasiparticle called magnon using a magnetic field or spatially asymmetric exchange couplings. Here, we propose a general framework to explore such spin textures in arbitrary insulating antiferromagnets. We introduce an analytical method to transform any complicated Hamiltonian to the simple representation based on pseudospin degrees of freedom, which couples to the momentum-dependent fictitious "Zeeman field." The direction of the pseudospin on a Bloch sphere describes the degree of contributions from the two magnetic sublattices to the spin moment carried by the magnon. There, the "Zeeman field" determines the direction of the pseudospin and thus becomes the control parameter of the spin texture, which is explicitly described by the original model parameters. The framework enabled us to clarify the uncovered aspect of the Kitaev interaction, and further provides a tool to easily design or explore materials with intriguing magnetic properties. Since these spin textures can be a source of a pure spin current, the Kitaev materials A(2)PrO(3) (A = Li, Na) shall become a potential platform of power-saving spintronics devices.