Roles of easy-plane and easy-axis XXZ anisotropy and bond alternation in a frustrated ferromagnetic spin-1/2 chain
Roles of easy-plane and easy-axis XXZ anisotropy and bond alternation in a frustrated ferromagnetic spin-1/2 chain
复制标题
受抑铁磁自旋 1/2 链中易平面和易轴 XXZ 各向异性和键交替的作用
DOI：
10.1103/physrevb.101.224439
复制
发表时间：
2020
影响因子：
3.7
通讯作者：
Onoda Shigeki
中科院分区：
文献类型：
--
作者：
Ueda Hiroshi;Onoda Shigeki
具有铁磁性第一邻交换偶联和反铁磁性第二邻交换偶联的自旋-海森堡链具有具有极小自旋间隙的霍尔丹二聚体基态。因此基态很容易被扰动改变。在这里，我们研究了易轴型和易平面型的XXZ交换磁各向异性以及受挫铁磁自旋链的基态、自旋间隙和磁性质的变化。结果表明，在SU(2)对称情况下，存在两种截然不同的二聚自旋隙相，其中一种自旋隙和磁化率在SU(2)对称情况附近极小，另一种在远离SU(2)对称情况时较大。振幅的微小变化会迅速缩短自旋相关的间距，趋向于四自旋周期性，如在的极限。这些效应不足以定量地解释在实验中观察到的准一维自旋间隙磁电铜的总体磁性，其表现出被磁场稳定的铁电性。我们的结果也与最近在单链水平上发现的铁磁性链内和反铁磁性链间顺序有关。我们还通过映射到有效的自旋-1链模型揭示了模型中对称保护拓扑相变的性质。
The spin-Heisenberg chain with a ferromagnetic first-neighbor exchange couplingand an antiferromagnetic second-neighborhas a Haldane dimer ground state with an extremely small spin gap. Thus the ground state is readily altered by perturbations. Here, we investigate the effects of XXZ exchange magnetic anisotropy of both the easy-axis and easy-plane types and an alternation inon the ground state, the spin gap, and magnetic properties of the frustrated ferromagnetic spin-chain. It is found that there are two distinct dimerized spin-gap phases, in one of which the spin gap and the magnetic susceptibility are extremely small around the SU(2) symmetric case and in the other they are moderately large far away from the SU(2) symmetric case. A small alternation in the amplitude ofrapidly shortens the pitch of spin correlations towards the four-spin periodicity, as in the limit of. These effects are not sufficient to quantitatively explain overall experimentally observed magnetic properties in the quasi-one-dimensional spin-gapped magnetoelectric cupratethat exhibits ferroelectricity stabilized by a magnetic field. Our results are also relevant to, where the ferromagnetic intrachain and antiferromagnetic interchain order has recently been found, in a single chain level. We also reveal the nature of symmetry-protected topological phase transitions in the model by mapping onto effective spin-1 chain models.