Dynamic Critical Phenomena in Magnetic Systems. II

Abstract
It is predicted that the electrical resistivity tensor ρµν becomes anomalous and anisotropic near the antiferromagnetic critical point TN due to the critical scattering of conduction electrons by the localized spins. If |Kµ|, |Kν| ≫κ, where K is one half of the magnetic reciprocal lattice vector and κ is the inverse of the correlation length of the spin fluctuations, then the temperature derivative of the electrical resistivity (dρµν/dT) has an anomaly proportional to ε- (α+ γ-1), where ε= |T - TN|/TN and α and γ are the critical indices of the specific heat and the magnetic susceptibility, respectively. In typical antiferromagnets, α= 0 and γ= 4/3. Below TN, however, there appears a stronger anomaly of ε-(α+ γ)/2 due to the long range order. Thus the electrical resistivity turns out to have a peak near TN, whose maximum locates below TN and whose temperature derivative negatively diverges at TN. If |Kµ|, |Kν| ≪κ, then (dσµν/dT) must have the same anomaly as in the ferromagnetic metals, and thus would have a positive logarithmic divergence both above and below TN. We also found that if |Kµ|, |Kν|≫κ, then the thermal resistivity tensor Wµν shows the same anomaly as the electrical resistivity tensor ρµν.