High-field expansion approach to kagome antiferromagnets with Dzyaloshinskii-Moriya interactions
High-field expansion approach to kagome antiferromagnets with Dzyaloshinskii-Moriya interactions
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DOI：
10.1103/physrevb.100.121108
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发表时间：
2019-05
影响因子：
3.7
通讯作者：
Michael O. Flynn;Rajiv R. P. Singh
中科院分区：
文献类型：
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作者：
Michael O. Flynn;Rajiv R. P. Singh
我们应用链接簇扩展技术通过海森堡和 Dzyaloshinskii-Moriya 相互作用 (DMI) 研究 Kagome 晶格上自旋半反铁磁体的极化高场相。我们发现，当磁场位于 Kagome 平面时，没有 DMI 的单磁振子谱的狄拉克点对于任意 DMI 具有鲁棒性。与 DMI 使频谱间隙的典型情况不同，我们发现改变 DMI 只会改变狄拉克点的位置。相比之下，具有戈薇平面之外的分量的磁场会使光谱出现间隙，从而产生拓扑磁振子带。通过计算能带陈数，我们绘制出随着耦合变化的拓扑相图。观察到一对相变，我们发现相界附近的霍尔热导率增强。
We apply linked cluster expansion techniques to study the polarized high-field phase of a spin-half antiferromagnet on the Kagome lattice with Heisenberg and Dzyaloshinskii-Moriya interactions (DMI). We find that the Dirac points of the single-magnon spectrum without DMI are robust against arbitrary DMI when the magnetic field lies in the Kagome plane. Unlike the typical case where DMI gaps the spectrum, here we find that varying the DMI merely shifts the location of the Dirac points. In contrast, a magnetic field with a component out of the Kagome plane gaps the spectrum, leading to topological magnon bands. We map out a topological phase diagram as the couplings are varied by computing the band Chern numbers. A pair of phase transitions are observed and we find an enhanced thermal Hall conductivity near the phase boundary.