Specific Heat Due to Spin Fluctuations in Nearly and Weakly Antiferromagnetic Metals

The specific heat of nearly and weakly antiferromagnetic metals is discussed by using the renormalized spin fluctuation theory, which has been previously applied to the study of the effect of spin fluctuations on the magnetic susceptibility in antiferromagnetic metals. The coefficient of the linear specific heat enhanced by the effect of spin fluctuations, Δγ, is given as a function of α by Δγ(α)-Δγ(1)∝-|α-1| 1/2 for both paramagnetic and antiferromagnetic phases near the critical boundary (α=2 I χ S 0 , I is the exchange interaction, χ S 0 the staggered susceptibility for I =0). Although the enhanced linear specific heat is predominant at low temperatures, the effect is considerably suppressed because of the renormalization of spin fluctuations as the temperature increases. Numerical calculations are presented for the free electron model with Umklapp processes.