Waseda Institute for Advanced Study, Waseda University, Tokyo 169-8050, Japan.
Condensed Matter Theory Laboratory, RIKEN, Saitama 351-0198, Japan and Research and Education Center for Natural Sciences, Keio University, Kanagawa 223-8521, Japan.
Phys Rev Lett. 2015 Jan 16;114(2):027201. doi: 10.1103/PhysRevLett.114.027201.
Magnetization processes of spin-1/2 layered triangular-lattice antiferromagnets (TLAFs) under a magnetic field H are studied by means of a numerical cluster mean-field method with a scaling scheme. We find that small antiferromagnetic couplings between the layers give rise to several types of extra quantum phase transitions among different high-field coplanar phases. Especially, a field-induced first-order transition is found to occur at H≈0.7H_{s}, where H_{s} is the saturation field, as another common quantum effect of ideal TLAFs in addition to the well-established one-third plateau. Our microscopic model calculation with appropriate parameters shows excellent agreement with experiments on Ba_{3}CoSb_{2}O_{9} [T. Susuki et al., Phys. Rev. Lett. 110, 267201 (2013)]. Given this fact, we suggest that the Co^{2+}-based compounds may allow for quantum simulations of intriguing properties of this simple frustrated model, such as quantum criticality and supersolid states.
通过采用标度方案的数值团簇平均场方法，研究了磁场 H 下自旋为 1/2 的层状三角晶格反铁磁体（TLAFs）的磁化过程。我们发现，层间较小的反铁磁耦合导致了不同高磁场共面相中几种类型的额外量子相变。特别是，我们发现，在 H≈0.7H_{s}处发生了场诱导的一级相变，其中 H_{s}是饱和场，这是除了已确立的三分之一平台之外，理想 TLAFs 的另一种常见量子效应。我们用适当参数进行的微观模型计算与 Ba_{3}CoSb_{2}O_{9}上的实验[T. Susuki 等人，Phys. Rev. Lett. 110, 267201 (2013)]吻合得很好。鉴于这一事实，我们建议基于 Co^{2+}的化合物可能允许对这个简单的受挫模型的有趣性质进行量子模拟，例如量子临界点和超流态。
