Semiclassical ground-state phase diagram and multi- Q phase of a spin-orbit-coupled model on triangular lattice
Semiclassical ground-state phase diagram and multi- Q phase of a spin-orbit-coupled model on triangular lattice
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DOI：
10.1103/physrevb.94.174424
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发表时间：
2016-07
影响因子：
3.7
通讯作者：
Changle Liu;Xiaoqun Wang;R. Yu
中科院分区：
文献类型：
--
作者：
Changle Liu;Xiaoqun Wang;R. Yu
受最近对受抑量子磁性化合物YbMgGaO 4的实验研究的启发，我们研究了三角晶格上考虑自旋轨道耦合效应的有效自旋模型.我们确定了该模型的经典基态相图，其中包括一个120度的尼尔和两个共线的反铁磁相。在Neel和共线相之间的相边界附近，我们确定了三个中间非共线反铁磁相。在每一个他们的磁矩是有序的多个无公度波矢量Q值。通过线性自旋波理论，我们进一步研究了该模型中量子涨落的影响。我们发现，非共线多Q反铁磁态的自旋激发能隙是有限的，但可以非常小，并且在某些大的J_{z+-}区域，在强量子涨落下，该态不稳定于自旋液相.
Motivated by recent experiments on the frustrated quantum magnetic compound YbMgGaO4, we study an effective spin model on triangular lattice taking into account the effects of the spin-orbit coupling. We determine the classical ground-state phase diagram of this model, which includes a 120 degree Neel and two collinear antiferromagnetic phases. In the vicinity of the phase boundary between the Neel and collinear phases, we identify three intermediate non-collinear antiferromagnetic phases. In each of them the magnetic moments are ordered at multiple incommensurate wave vector Q values. We further study the effects of quantum fluctuations in this model via a linear spin-wave theory. We find that the spin excitation gap of the non-collinear multi-Q antiferromagnetic state is finite but can be vanishingly small, and this state is unstable to a spin liquid phase under strong quantum fluctuations in some large J_{z+-} regime.