This article is cited in 2 papers

Magnetic phase transitions in spin-fluctuation theory

N. B. Melnikov, G. V. Paradezhenko

Lomonosov Moscow State University, Moscow, Russia

Abstract: A first-order phase transition is a characteristic feature of the Gaussian approximation in spin-fluctuation theory. We propose a method for taking the fourth-order terms of the free energy expansion into account using partial averaging. In the example of the Ising model, we show that renormalization of the magnetic susceptibility leads to a second-order phase transition, which is experimentally observed in metals. We use the parameter substitution method to compute the temperature dependence at high temperatures.

Keywords: functional integral method, Stratonovich–Hubbard transformation, partial averaging, renormalization.

Received: 08.09.2014
Revised: 02.01.2015

DOI: 10.4213/tmf8789

 English version: Theoretical and Mathematical Physics, 2015, 183:3, 868–877

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