Source: School of Physics
Written by: School of Physics
Edited by: Wang Dongmei

Prof. Dao-Xin Yao’s Group at School of Physics and State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, published a research paper entitled “Anomalous Quantum-Critical Scaling Corrections in Two-Dimensional Antiferromagnets” in Physical Review Letters in September 2018, which resolves a long-standing issue in quantum phase transition.

Quantum phase transition is a kind of phase transition at zero temperature driven by quantum fluctuations. One of the best known quantum phase transitions is that between Neel antiferromagnetic (AFM) and quantum paramagnetic ground states in 2D dimerized Heisenberg model, which is supposed to be 3D O(3) universality class. However, a longstanding unresolved issue is the differences observed in QMC calculations between two classes of dimer patterns shown in the figure.
 

Prof. Dao-Xin Yao’s Group aims at this problem and studies the Neel-paramagnetic quantum phase transition in two-dimensional dimerized S=1/2 Heisenberg antiferromagnets using finite-size scaling of quantum Monte Carlo data. They resolved the long-standing issue of the role of cubic interactions arising in the bond-operator representation when the dimer pattern lacks a certain symmetry. They find nonmonotonic (monotonic) size dependence in the staggered (columnar) dimerized model, where cubic interactions are (are not) present. They conclude that there is a new irrelevant field in the staggered model, but, at variance with previous claims, it is not the leading irrelevant field. Their study shows that the staggered dimer model and columnar dimer model have the same 3D O(3) quantum phase transition. Their study serves as an example of finite-size behaviors that may at first sight appear puzzling but can be understood once the possibility of competing scaling corrections is recognized.

This work has been published in Physical Review Letters (Physical Review Letters 121, 117202 (2018), DOI: 10.1103/PhysRevLett.121.117202). This research was done by Prof. Dao-Xin Yao’s group together with Prof. Anders Sandvik at Boston University and Prof. Wenan Guo at Beijing Normal University.

Prof. Dao-Xin Yao’s group has made a series of achievements in the field of quantum magnetism of correlated electron systems. For example, they have investigated the itinerancy-enhanced quantum fluctuation of magnetic moments in iron-based superconductors (Phys. Rev. Lett. 115, 117001 (2015)), studied universal short-time quantum critical dynamics of finite-size systems (Phys. Rev. B 96, 094304(2017)), got the exact partition function and phase diagrams of XXZ-Ising model on the triangular kagome lattice with spin 1 on the decorated trimers (Phys. Rev. E 98, 012127 (2018)).

This work was supported by the National Natural Science Foundation of China, National Basic Research Program of China, State Key Laboratory of Optoelectronic Materials and Technologies, and the Leading Talent Program of Guangdong Special Projects.

Link to the paper: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.117202