Magnetic properties and cryogenic magnetocaloric effects of rare earth fluorides NH4RE3F10 (RE = Tb, Dy, Ho, Er)

The magnetic properties and magnetocaloric effects of rare earth fluorides NH4RE3F10 (RE = Tb, Dy, Ho and Er) were investigated firstly in NH4-RE-F system. The chi(T) curves show that the materials exhibit a paramagnetic-like behavior and high thermal reversibility. The Curie-Weiss fitting gives that there is an antiferromagnetic interaction between the magnetic moments of RE ions in these materials. Based on the magnetic isotherms data, the values of -Delta Sm(T) in the cases of Delta H =10, 20 and 50 kOe were calculated. In the case of Delta H =10 kOe, the -Delta Sm(T) of NH4Er3F10 is the largest and the maximum value is about twice as large as that of Gd3Ga5O12(GGG). It indicates that the NH4Er3F10 materials may be candidates of low-field-driven cryogenic magnetic coolant.