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., ${A}_{p}{B}_{1\ensuremath{-}p}$, where $A$ and $B$ have ferromagnetic and antiferromagnetic phase transitions). The tetracritical (bicritical) exponents are possibly given by the $n=0$ value of their $\ensuremath{\epsilon}$ expansions. In particular, the crossover exponent $\ensuremath{\phi}$, describing the shape of the $p\ensuremath{-}T$ phase diagram near the tetracritical point, is exactly equal to 1. This explains various experiments.