Novel Spin-Liquid States in the Frustrated Heisenberg Antiferromagnet on the Honeycomb Lattice
Novel Spin-Liquid States in the Frustrated Heisenberg Antiferromagnet on the Honeycomb Lattice
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DOI：
10.1143/jpsj.79.114705
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发表时间：
2010-11-01
影响因子：
1.7
通讯作者：
Motome, Yukitoshi
中科院分区：
文献类型：
--
作者：
Okumura, Soichiro;Kawamura, Hikaru;Motome, Yukitoshi
最近对蜂窝晶格海森堡反铁磁体Bi3Mn4O12(NO3)的实验揭示了低温下一种新的类自旋-液体行为，这归因于海森堡反铁磁体最近邻和次最近邻相互作用J(1)和J(2)之间的竞争所产生的受挫效应。受实验的启发，我们用低温展开和蒙特卡罗模拟研究了蜂窝晶格上J(1)-J(2)受挫经典Heisenberg AF的有序性。众所周知，该模型具有基态的大规模简并，然而，由于热涨落导致独特的有序状态，这种简并可能会被取消，这种效应被称为“按无序排序”。我们发现，该模型呈现出有趣的有序化行为，特别是在AF相界附近。无序有序的能量尺度在那里被抑制到极低的温度，产生了奇异的自旋-液体状态，比如伴随着特征的自旋结构因子和场致反铁磁性的“环状液体”或“煎饼液体”状态。我们认为，如果系统处于如此奇异的自旋-液体状态，那么最近的实验数据是可以解释的。
Recent experiment on a honeycomb-lattice Heisenberg antiferromagnet (AF) Bi3Mn4O12(NO3) revealed a novel spin-liquid-like behavior down to low temperature, which was ascribed to the frustration effect due to the competition between the AF nearest-and next-nearest-neighbor interactions J(1) and J(2). Motivated by the experiment, we study the ordering of the J(1)-J(2) frustrated classical Heisenberg AF on a honeycomb lattice both by a low-temperature expansion and a Monte Carlo simulation. The model has been known to possess a massive degeneracy of the ground state, which, however, might be lifted due to thermal fluctuations leading to a unique ordered state, the effect known as "order-by-disorder". We find that the model exhibits an intriguing ordering behavior, particularly near the AF phase boundary. The energy scale of the order-by-disorder is suppressed there down to extremely low temperatures, giving rise to exotic spin-liquid states like a "ring-liquid" or a "pancake-liquid" state accompanied by the characteristic spin structure factor and the field-induced antiferromagnetism. We argue that the recent experimental data are explicable if the system is in such exotic spin-liquid states.