Theoretical Study of the Multiferroic Behavior of the Magnetic Relaxor Ferroelectric CdCr2S4

Using a microscopic model and the replica method as well as the Green’s function theory, we have investigated the relaxor and multiferroic behavior of CdCr2S4. The magnetization, the remanent polarization Pr and the real part of the dielectric function are studied theoretically as a function of temperature, with and without a magnetic field, respectively. The magnetization and the polarization exist together below the magnetic phase transition temperature. Pr decreases whereas increases and the peak shifts to smaller temperature values with increasing magnetic field h. Moreover, the temperature and electric field E dependence of the magnetization M is also discussed. A kink is observed around the ferroelectric transition temperature. The kink is deeper for stronger electric fields and anharmonic spin-phonon interactions.