Critical behavior and universality properties of uniaxial ferromagnetic thin films in the presence of random magnetic fields

摘要

Critical phenomena in uniaxial ferromagnetic thin films in the presence ofrandom magnetic fields have been studied within the framework of effectivefield theory. When the type of the random field distribution is bimodal, thesystem exhibits tricritical behavior. Furthermore, the critical value ofsurface to bulk ratio of exchange interactions at which the transitiontemperature becomes independent of film thickness is insensitive to thepresence of disorder whether the distribution is bimodal or trimodal. Regardingthe universality properties, neither $p$, nor $h$ variations in the system canaffect the value of the shift exponent $\lambda$. In this regard, it can beconcluded that pure ferromagnetic thin films are in the same universality classwith those under the influence of random discrete magnetic fields.