Japaridze G I, Cheraghi Hadi, Mahdavifar Saeed
Center for Condensed Matter Theory and Quantum Computations Ilia State University, Tbilisi, Georgia.
Department of Physics, University of Guilan, 41335-1914, Rasht, Iran.
Phys Rev E. 2021 Jul;104(1-1):014134. doi: 10.1103/PhysRevE.104.014134.
We consider the ground-state phase diagram of a one-dimensional spin-1/2 XXZ chain with a spatially modulated Dzyaloshinskii-Moriya interaction in the presence of an alternating magnetic field applied along the z[over ̂] axis. The model is studied using the continuum-limit bosonization approach and the finite system exact numerical technique. In the absence of a magnetic field, the ground-state phase diagram of the model includes, besides the ferromagnetic and gapless Luttinger-liquid phases, two gapped phases: the composite (C1) phase characterized by the coexistence of long-range-ordered (LRO) alternating dimerization and spin chirality patterns, and the composite (C2) phase characterized by, in addition to the coexisting spin dimerization and alternating chirality patterns, the presence of LRO antiferromagnetic order. In the case of mentioned composite gapped phases, and in the case of a uniform magnetic field, the commensurate-incommensurate type quantum phase transitions from a gapful phase into a gapless phase have been identified and described using the bosonization treatment and finite chain exact diagonalization studies. The upper critical magnetic field corresponding to the transition into a fully polarized state has been also determined. It has been shown that the very presence of a staggered component of the magnetic field vapes the composite (C1) in favor of the composite gapped (C2) phase.
我们考虑了一维自旋-1/2 XXZ链的基态相图，该链具有空间调制的Dzyaloshinskii-Moriya相互作用，且存在沿z轴施加的交变磁场。使用连续极限玻色化方法和有限系统精确数值技术对该模型进行了研究。在没有磁场的情况下，该模型的基态相图除了铁磁相和无隙卢廷格液体相之外，还包括两个有隙相：复合（C1）相，其特征是长程有序（LRO）交替二聚化和自旋手征模式共存；复合（C2）相，其特征是除了共存的自旋二聚化和交替手征模式外，还存在LRO反铁磁序。在上述复合有隙相的情况下，以及在均匀磁场的情况下，已经通过玻色化处理和有限链精确对角化研究确定并描述了从有隙相到无隙相的 commensurate-incommensurate 型量子相变。还确定了对应于转变为完全极化状态的上临界磁场。结果表明，磁场交错分量的存在确实会使复合（C1）相消失，而有利于复合有隙（C2）相。
