Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1810092 | Physica B: Condensed Matter | 2013 | 4 Pages |
Abstract
The behavior of a three-dimensional isotropic Heisenberg ferromagnet in the presence of a magnetic field H is investigated in the random phase approximation (RPA) near the Curie temperature Tc. It is shown that the magnetization M at the Curie temperature Tc is described by the law M(T=Tc)â¼H1/5 and the initial magnetic susceptibility Ï0 at temperatures Tâ¥Tc is given by Ï0(Tâ¥Tc)â¼(TâTc)â2. It means that in the RPA the critical exponents for a three-dimensional Heisenberg ferromagnet coincide with the critical exponents for the Berlin-Kac spherical model of a ferromagnet rather than with the critical exponents of the mean field approximation (MFA). Hence it follows as well that, when a magnetic field H is risen from H=0 to H=Ha, the magnetic entropy SM will be decreased as ÎSM(T=Tc)â¼âHa4/5 at the Curie temperature Tc and as ÎSM(T>Tc)â¼â(TâTc)â3Ha2 at temperatures T>Tc.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
E.E. Kokorina, M.V. Medvedev,