近日，英国兰卡斯特大学的R. V. Mikhaylovskiy及其研究小组与荷兰拉德堡大学的D. Afanasiev等人合作并取得一项新进展。经过不懈努力，他们发现倾斜自旋有序可作为磁振子超快转换的平台。相关研究成果已于2024年5月29日在国际权威学术期刊《自然》上发表。

据悉，传统上，磁性固体分为两大类:铁磁体和反铁磁体，分别具有平行和反平行的自旋有序。虽然通常反铁磁体的磁化强度为零，但在某些反铁磁体中，由于强自旋-轨道耦合，会产生额外的反对称自旋-自旋相互作用，导致自旋倾斜，从而产生净磁化。

倾斜反铁磁体将反铁磁有序与铁磁体的典型现象结合起来，在自旋电子学和磁振子学方面具有很大的潜力。通过这种方式，它们可以被确定为与最近提出的新型磁性材料——交错磁体——密切相关。交错磁体被预测具有强磁光效应，太赫兹频率自旋动力学和手性自旋波的简并度提升(即，在倾斜反铁磁体中存在的所有效应)。

该研究团队通过利用独特的现象，揭示了磁振子倾斜自旋有序的新颖功能，并证明其能够推动利用超快激光脉冲触发的非线性磁振子相互作用，实现将布里渊区中心的磁振子转化为传播磁振子的机制。这项实验结果和理论分析都表明，自旋倾斜可以实现这一机制。

附：英文原文

Title: Canted spin order as a platform for ultrafast conversion of magnons

Author: Leenders, R. A., Afanasiev, D., Kimel, A. V., Mikhaylovskiy, R. V.

Issue&Volume: 2024-05-29

Abstract: Traditionally, magnetic solids are divided into two main classes—ferromagnets and antiferromagnets with parallel and antiparallel spin orders, respectively. Although normally the antiferromagnets have zero magnetization, in some of them an additional antisymmetric spin–spin interaction arises owing to a strong spin–orbit coupling and results in canting of the spins, thereby producing net magnetization. The canted antiferromagnets combine antiferromagnetic order with phenomena typical of ferromagnets and hold great potential for spintronics and magnonics. In this way, they can be identified as closely related to the recently proposed new class of magnetic materials called altermagnets. Altermagnets are predicted to have strong magneto-optical effects, terahertz-frequency spin dynamics and degeneracy lifting for chiral spin waves (that is, all of the effects present in the canted antiferromagnets). Here, by utilizing these unique phenomena, we demonstrate a new functionality of canted spin order for magnonics and show that it facilitates mechanisms converting a magnon at the centre of the Brillouin zone into propagating magnons using nonlinear magnon–magnon interactions activated by an ultrafast laser pulse. Our experimental findings supported by theoretical analysis show that the mechanism is enabled by the spin canting.

DOI: 10.1038/s41586-024-07448-3

Source: https://www.nature.com/articles/s41586-024-07448-3