Magnetic orderings and phase separations in a simple model of insulating systems
Authors:
- Konrad Jerzy Kapcia,
- Szymon Murawski,
- Waldemar Kłobus,
- Stanisław Robaszkiewicz
Abstract
A simple effective model for a description of magnetically ordered narrow-band insulators is studied. The Hamiltonian considered consists of the effective on-site interaction (U) and intersite magnetic exchange interactions (Jz, Jxy) between nearest-neighbours. The phase diagrams and properties of this model for arbitrary chemical potential μ and arbitrary electron density n have been determined within several approaches: (i) the variational method (which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation) for any Jz,Jxy≠0 (exact in the limit of infinite dimensions), (ii) the Monte Carlo simulations on a square lattice with periodic boundary conditions for Jxy=0, and (iii) other approximate methods (inter alia: random phase approximation and spin-wave approximation) as well as (iv) rigorous treatment to obtain results concerning the ground state phase diagrams (the two last also for Jz,Jxy≠0). The investigations of the general case show that, depending on the values of interaction parameters and electron concentration n, the system can exhibit not only homogeneous phases: (anti-)ferromagnetic (Fα, α=z,xy) and nonordered (NO), but also phase separated states (PSα: Fα/NO). For a fixed n one finds the following phase transitions (both continuous and discontinuous ones) and their sequences, which can occur with increasing temperature: Fα→NO, PSα→NO, PSα→Fα→NO, PSα→Fα→PSα→NO. The system analysed exhibits also tricritical behaviour.
- Record ID
- UAM5b1f8a30a4514d2db5876acb23c9f880
- Author
- Journal series
- Physica A-Statistical Mechanics and Its Applications, ISSN 0378-4371
- Issue year
- 2015
- Vol
- 437
- Pages
- 218-234
- ASJC Classification
- ;
- DOI
- DOI:10.1016/j.physa.2015.05.074 Opening in a new tab
- Language
- (en) English
- Score (nominal)
- 30
- Score source
- journalList
- Score
- Publication indicators
- = 7; : 2015 = 1.131; : 2015 (2 years) = 1.785 - 2015 (5 years) =1.738
- Citation count
- 10
- Uniform Resource Identifier
- https://researchportal.amu.edu.pl/info/article/UAM5b1f8a30a4514d2db5876acb23c9f880/
- URN
urn:amu-prod:UAM5b1f8a30a4514d2db5876acb23c9f880
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or PerishOpening in a new tab system.