RANDOM FIELD EFFECTS IN DISORDERED ANISOTROPIC ANTI-FERROMAGNETS

A uniform magnetic field is shown to generate random local fields in uniaxially anisotropic antiferromagnets with random exchange interactions. This leads to a stronger divergence of the temperature derivative of the static susceptibility even at zero field, and to a drastic change in the critical exponents at the Ising-like antiferromagnetic transition as well as at the tricritical or bicritical points occurring at finite fields.