Current status of spin fluctuation theory of magneto-volume effects in itinerant electron magnets

Abstract

Magneto-volume effect means the phenomena where volume of magnet changes spontaneously with temperature or as the effect of externally applied magnetic field. In this review, we show that they are treated in the same way as the thermal expansion of solids due to lattice vibrations. In this treatment of the effect on itinerant electron magnets, the same free energy is used in the derivation of magnetic entropy and specific heat. According to its volume dependence, three independent magneto-volume coupling constants are also introduced. As the results, our magneto-volume striction consists of two different components. In this way, we show quite new properties are derived and compared well with some results of experiments.