Dynamic Critical Phenomena in Magnetic Systems. II : Electrical Resistivity near the Neel Point

概要

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It is predicted that the electrical resistivity tensor ρ_<μν> becomes anomalous and anisotropic near the antiferromagnetic critical point T_N due to the critical scattering of conduction electrons by the localized spins. If |K_μ|, |K_ν|≫k, where K is one half of the magnetic reciprocal lattice vector and k is the inverse of the correlation length of the spin fluctuations, then the temperature derivative of the electrical resistivity (dρ_<μν>/dT) has an anomaly proportional to ε^<-(α+γ-1)>, where ε=T-T_N|/T_N 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 T_N, 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 T_N, whose maximum locates below T_N and whose temperature derivative negatively diverges at T_N. If |K_μ|, |K_ν|≪k, then (dρ_<μν>/dT) must have the same anomaly as in the ferromagnetic metals, and thus would have a positive logarithmic divergence both above and below T_N. We also found that if |K_μ|, |K_ν|≫k, then the thermal resistivety tensor W_<μν> shows the same anomaly as the electrical resistivity tensor ρ_<μν>.
理論物理学刊行会の論文
1969-05-25