Spin-Fluctuation Contributions to the Specific Heat

Abstract

The specific heat is calculated for weakly ferromagnetic and nearly ferromagnetic metals. These systems are characterized by an enhanced susceptibility indicating large spin fluctuations. An expression for the mass enhancement on both sides of the ferromagnetic instability is presented. The specific heat just above the Curie temperature is investigated. In this region, the terms which lead to the large low-temperature mass enhancements are greatly reduced, and a new term contributes a singular specific heat at the Curie temperature. Spin-fluctuation contributions to the low-temperature specific heat are calculated for both phases, and numerical results are presented. Very large magnetic fields are shown to be effective in reducing the strongly enhanced specific heat. Calculations of the temperature dependence of the specific heat due to spin fluctuations in the paramagnetic phase are compared with the experimental results on ${\mathrm{He}}^{3}$.