Random‐field mechanism in random‐bond multicritical systems (abstract)

It is argued on general grounds that bond randomness drastically alters multicritical phase diagrams via a random‐field mechanism. For example, tricritical points and critical endpoints are entirely eliminated (in spatial dimension d≤2) or depressed in temperature (d>2). These predictions are confirmed by a renormalization‐group calculation.¹ Another consequence of this phenomenon is that, under bond randomness, the phase transitions of q‐state Potts models are second order for all q at dimensionality d≤2.