Quantum effects in a half-polarized pyrochlore antiferromagnet.
Quantum effects in a half-polarized pyrochlore antiferromagnet.
复制标题
DOI：
10.1103/physrevlett.96.097207
复制
发表时间：
2005-10
影响因子：
8.6
通讯作者：
D. Bergman;Ryuichi Shindou;G. Fiete;L. Balents
中科院分区：
文献类型：
--
作者：
D. Bergman;Ryuichi Shindou;G. Fiete;L. Balents
我们研究了在一个自旋为3/2的反铁磁体的烧绿石晶格在外部磁场中的量子效应，专注于在饱和值的一半，观察到在CdCr 2 O 4和HgCr 2 O 4的磁化的高原附近。我们的理论，基于量子涨落，预测存在一个稳定的破缺状态的平台上，即使只有最近邻微观交换。这种破缺态是由平行和反平行于磁场的自旋以3：1的比例在每个四面体上的特殊排列组成的。它使晶格晶胞变为四倍，并将空间群从Fd 3 m减小到P4（3）32。我们还预测，在平台之上的领域，低温相具有横向自旋顺序，可描述为玻色-爱因斯坦凝聚的磁振子。其他的比较和建议的实验进行了讨论。
We study quantum effects in a spin-3/2 antiferromagnet on the pyrochlore lattice in an external magnetic field, focusing on the vicinity of a plateau in the magnetization at half the saturation value, observed in CdCr2O4 and HgCr2O4. Our theory, based on quantum fluctuations, predicts the existence of a symmetry-broken state on the plateau, even with only nearest-neighbor microscopic exchange. This symmetry-broken state consists of a particular arrangement of spins polarized parallel and antiparallel to the field in a 3:1 ratio on each tetrahedron. It quadruples the lattice unit cell, and reduces the space group from Fd3m to P4(3)32. We also predict that for fields just above the plateau, the low-temperature phase has transverse spin order, describable as a Bose-Einstein condensate of magnons. Other comparisons to and suggestions for experiments are discussed.