Calculation of nonlinear magnetic susceptibility tensors for a uniaxial antiferromagnet

In this paper, we present a derivation of the nonlinear susceptibility tens ors for a two-sublattice uniaxial antiferromagnet up to the third-order eff ects within the standard definition by which the rf magnetization m is defi ned as a power series expansion in the rf fields h with the susceptibility tensors <(<chi>)over left right arrow>((q)) as the coefficients. The starti ng point is the standard set of torque equations of motion for this problem . A complete set of tensor elements is derived for the case of a single-fre quency input wave. Within a circular polarization frame (pnz) expressions a re given for the first-order susceptibility, second-harmonic generation, op tical rectification, third-harmonic generation and intensity-dependent susc eptibility. Some of the coefficients with representative resonance features in the far infrared are illustrated graphically and we conclude with a bri ef discussion of the implications of the resonance features arising from th e calculations and their potential applications.