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)

Television pictures of Phobos: first results

In February-March 1989, 37 television images of the Martian satellite Phobos were obtained by the Phobos 2 spacecraft from distances of 200-1100 km. These images provide an important supplement to the TV data from the American Mariner 9 and Viking spacecraft in coverage of t4e surface of Phobos and in resolution in certain regions, in spectral range, and in range of phase angles. They make it possible to refine the figure and topographic and geological maps of the surface of Phobos, its spectral and angular reflective characteristics, the surface composition and texture, and characteristics of the orbital and librational motion