Optical bistability (OB) and optical multistability (OM) behavior in molecular magnets is theoretically studied. It is demonstrated that the OB of the system can be controlled via adjusting the magnetic field intensity. In addition, it is shown that the frequency detuning of probe and coupling fields, as well as the cooperation parameter, has remarkable effects on the OB behavior of the system. Also, we find that OB can be converted to OM through the magnitude of control-field detuning. Our results can be used as a guideline for optimizing and controlling the switching process in the crystal of molecular magnets.
\nA general model for intrinsic optical bistability is presented for\natomic or molecular systems which can be decomposed into two weakly\ninteracting subsystems. It is shown that optical bistability should\noccur when the interaction between the two subsystems fluctuates\nfaster than the characteristic time of the interaction. The validity\nof the model is demonstrated in the case of magnetic bistability of\nconduction electrons. It is extended in the infrared or visible\nrange with pairs of rare earth ions and rare earth-transition metal\nions systems.\n