Topological Spin Excitations in Honeycomb Ferromagnet CrI3
Topological Spin Excitations in Honeycomb Ferromagnet CrI3
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DOI：
10.1103/physrevx.8.041028
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发表时间：
2018-07
期刊：
影响因子：
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通讯作者：
Lebing Chen;Jae-Ho Chung;B. Gao;Tong Chen;M. Stone;A. Kolesnikov;Qingzhen Huang;P. Dai
中科院分区：
文献类型：
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作者：
Lebing Chen;Jae-Ho Chung;B. Gao;Tong Chen;M. Stone;A. Kolesnikov;Qingzhen Huang;P. Dai
在二维蜂窝状铁磁体中，玻色子磁振子准粒子（自旋波）可以表现为无质量狄拉克费米子，也可以形成拓扑保护的边缘态。定义其性质的关键因素是次近邻 Dzyaloshinskii-Moriya 相互作用，它打破了晶格的反演对称性并区分了相关自旋波激发的手性。利用非弹性中子散射，我们发现绝缘蜂窝状铁磁体 CrI3 (TC=61K) 的自旋波具有两个独特的铁磁激发带，在狄拉克点处由约 4 meV 的间隙隔开。这些结果只能通过考虑具有 Dzyaloshinskii-Moriya 相互作用的海森堡哈密顿量来理解，从而提供实验证据，证明 CrI3 中的自旋波可以具有鲁棒的拓扑特性，对于无耗散自旋电子应用可能有用。
In two-dimensional honeycomb ferromagnets, bosonic magnon quasiparticles (spin waves) may either behave as massless Dirac fermions or form topologically protected edge states. The key ingredient defining their nature is the next-nearest-neighbor Dzyaloshinskii-Moriya interaction that breaks the inversion symmetry of the lattice and discriminates chirality of the associated spin-wave excitations. Using inelastic neutron scattering, we find that spin waves of the insulating honeycomb ferromagnet CrI3 (TC=61K) have two distinctive bands of ferromagnetic excitations separated by a ∼4 meV gap at the Dirac points. These results can only be understood by considering a Heisenberg Hamiltonian with Dzyaloshinskii-Moriya interaction, thus providing experimental evidence that spin waves in CrI3 can have robust topological properties potentially useful for dissipationless spintronic applications.