Tetracritical Points in Mixed Magnetic Crystals

Abstract

Recently developed renormalization-group techniques are used to study the tetracritical (or bicritical) point of quenched mixed magnetic crystals (e.g., $A_p{B}_{1-p}$, where $A$ and $B$ have ferromagnetic and antiferromagnetic phase transitions). The tetracritical (bicritical) exponents are possibly given by the $n=0\mathrm{}$ value of their $\epsilon$ expansions. In particular, the crossover exponent $\varphi$, describing the shape of the $p-T$ phase diagram near the tetracritical point, is exactly equal to 1. This explains various experiments.