The study of mixed spin-1 and spin-1/2: Entropy and isothermal entropy change


ALBAYRAK E.

Physica A: Statistical Mechanics and its Applications, vol.559, 2020 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 559
  • Publication Date: 2020
  • Doi Number: 10.1016/j.physa.2020.125079
  • Title of Journal : Physica A: Statistical Mechanics and its Applications
  • Keywords: Blume-Capel, Mixed-spin, Entropy, Isothermal entropy, Bethe lattice, Exact recursion relations, TEMPERATURE SERIES EXPANSION, QUADRATIC ISING FERROMAGNET, MAGNETOCALORIC PROPERTIES, CRITICAL-BEHAVIOR, MONTE-CARLO, CURIE-TEMPERATURE, CRYSTAL-FIELD, AB-INITIO, MODEL, SYSTEM

Abstract

The entropy and isothermal entropy change of the mixed spin-(1,1/2) Ising model are examined on the Bethe lattice by using the exact recursion relations (ERR) for the coordination numbers q = 3, 4 and 6. It is found that entropy presents a little kink at the second-order phase transitions and increases as q decreases for zero external magnetic field (H). As the crystal field (D) increases, the temperatures of the lines move to higher temperatures and they all combine together with further increase of temperature for each q. When H is introduced, the kinks disappear and the lines move to higher temperatures as D increases for given H. The peaks of isothermal entropy change increase as H-max, increases. The peaks are higher for appropriate values of D and H-max with lower q's. Two exceptions occur at higher H-max and lower negative D's, i.e. the peaks for higher q can extend beyond the one for lower q. (C) 2020 Elsevier B.V. All rights reserved.