Phase diagrams of a 2D Ising spin-pseudospin model

We consider the competition of magnetic and charge ordering in high-Tc cuprates within the framework of the simplified static 2D spin-pseudospin model. This model is equivalent to the 2D dilute antiferromagnetic (AFM) Ising model with charged impurities. We present the mean-field results for the system under study and make a brief comparison with classical Monte Carlo (MC) calculations. Numerical simulations show that the cases of strong exchange and strong charge correlation differ qualitatively. For a strong exchange, the AFM phase is unstable with respect to the phase separation (PS) into the charge and spin subsystems, which behave like immiscible quantum liquids. An analytical expression was obtained for the PS temperature.Comment: 14 pages, 3 figure

Competition between the Spin and Pseudospin Subsystems in a Model Cuprate

Abstract: The competition between the magnetic and charge orderings in a model cuprate is considered in terms of a simplified static 2D spin–pseudospin model. This model is equivalent to the 2D dilute antiferromagnetic (AFM) Ising model with charged impurities. The mean-field approximation results are presented for the system under study and briefly compared to the classical Monte Carlo (MC) calculations. The numerical simulation shows that the cases of the strong exchange and the strong charge correlation differ qualitatively. In the case of a strong exchange, the AMF phase is instable with respect to the phase separation (PS) into the pseudospin (charge) and magnetic (spin) subsystems that behave as immiscible quantum liquids. The analytical expression has been obtained for the PS temperature. © 2019, Pleiades Publishing, Ltd.Russian Foundation for Basic Research, РФФИ: 18-32-00837\18; Ministry of Education and Science of the Russian Federation, Minobrnauka: 2277, 5719; Government Council on Grants, Russian FederationFUNDING This work was supported by Program 211 of the Government of the Russian Federation (Agreement 02.A03.21.0006), the Ministry of Education and Science of the Russian federation (projects nos. 2277 and 5719), and the Russian Foundation for Basic Research (project no. 18-32-00837\18)