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Critical properties of xy model on two-layer Villain-ferromagnetic lattice

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Chinese Physics B 2004年第2期13卷 251-257页

作者：王漪 R.Quartu 刘晓彦韩汝琦 HoriguchiTsuyoshi InstituteofMicroelectronics PekingUniversityBeijing100871China DepartmentofComputerandMathematicalSciences GSISTohokuUniversity04Sendai980-8579Japan

We investigate phase transitions of the xy model on a two-layer square lattice which consists of a Villain plane(J) and a ferromagnetic plane (I), using Monte Carlo simulations and a histogram method. Depending on the values of interaction parameters (I, J), the system presents three phases: namely, a Kosterlitz-Thouless (KT) phase in which the two planes are critical for I predominant over J, a chiral phase in which the two planes have a chiral order for J predominant over I and a new phase in which only the Villain plane has a chiral order and the ferromagnetic plane is paramagnetic with a small value of chirality. We clarify the nature of phase transitions by using a finite size scaling method. We find three different kinds of transitions according to the values of (I, J): the KT transition, the Ising transition and an xy-Ising transition with v = 0.849(3). It turns out that the Ising or xy-Ising transition is associated with the disappearance of the chiral order in the Villain plane.

关键词： xy model chirality KT transition two-layer Villain lattice

Monogamy quantum correlation near the quantum phase transitions in the two-dimensional xy spin systems

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Chinese Physics B 2018年第6期27卷 137-144页

作者： Meng Qin Zhongzhou Ren Xin Zhang Department of General Education Army Engineering University of PLA Nanjing 211101 China Department of Physics Nanfing University Nanjing 210093 China School of Physics Science and Engineering Tongji University Shanghai 200092 China

We investigate the role of quantum correlation around the quantum phase transitions by using quantum renormalization group theory. Numerical analysis indicates that quantum correlation as well as quantum nonlocality can efficiently detect the quantum critical point in the two-dimensional xy systems. The nonanalytic behavior of the first derivative of quantum correlation is observed at the critical point as the size of the model increases. Furthermore, we discuss the quantum correlation distribution in this system based on the square of concurrence（SC） and square of quantum discord（SQD）. The monogamous properties of SC and SQD are obtained. Particularly, we prove that the quantum critical point can also be achieved by monogamy score.

关键词： xy model quantum phase transitions quantum correlation monogamy relation

Quantum Correlations in Infinite xy Spin-1/2 Chains and Quantum Phase Transition

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Communications in Theoretical Physics 2013年第2期59卷 146-156页

作者：谭小东黄寿胜金柏琪 School of Physics and Electronic Information Engineering Wenzhou University

We examine the ability of quantum discord (QD) and entanglements (concurrence, EoF and negativity) to detect the critical points associated to quantum phase transitions (QPTs) for xy models, i.e., the isotropic xy model with three-spin interactions at zero temperature, and the anisotropic xy model in a transverse magnetic field h at finite temperatures. For the case of zero temperature, we found that both entanglements and QD can spotlight the critical points of QPTs for these two models. Moreover, QD versus distance M exhibits the long-range behavior of quantum correlation for the anisotropic xy model, while entanglement is short-ranged. For the case of finite temperatures, we found that negativity has the same behaviors with concurrence at or near transition points. Moreover, QD for the anisotropic xy model can increase with temperature even in the absence of a magnetic field.

关键词： thermal quantum discord quantum phase transition xy model

Monte Carlo Study of Planar Rotator model with Weak Dzyaloshinsky-Moriya Interaction

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Communications in Theoretical Physics 2006年第4X期46卷 663-667页

作者： SUN Yun-Zhou LIU Hui-Ping YI Lin Department of Physics and State Key Laboratory of Laser Technology~ Huazhong University of Science and Technology Wuhan 430074 China

With the help of an improvement Monte Carlo method, the Berezinskii-Kosterlitz-Thouless phase transition arising in two-dimensional planar rotator model with weak Dzyaloshinsky-Moriya （DM） interaction is investigated. The effects of the DM interaction on specific heat, susceptibility, and magnetization are simulated. The critical temperature of transitions is determined by the so-called Binder cumulant and the susceptibility of finite-size scaling. We find that the chiral Z2 symmetry reduced by the DM interactions plays an important role in a two-dimensional xy spin system, typically, the critical temperature is sensitive to weak DM spin couplings.

关键词： Monte Carlo method Berezinskii-Kosterlitz-Thouless phase transition Dzyaloshinsky-Moriya interaction xy model

Critical Properties of a Generalized Planar Rotator model

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Communications in Theoretical Physics 2012年第5期57卷 893-896页

作者：孙运周谭艳荣陈飞明 Department of Photoelectricity Wuhan Textile University Department of Physics Huazhong University of Science and Technology

The critical properties of the planar rotator model with chiral Dzyaloshinsky-Moriya interaction are analyzed using a hybrid Monte Carlo *** on different lattices conform an observation that there is an xy-like Berezinskii-Kosterlitz-Thouless (BKT) phase transition in this *** ground state and some thermodynamics properties are also discussed.

关键词： critical property phase transition xy model Monte Carlo method