First-Order-Like Antiferromagnetic Transition and Field-Induced Antiferroquadrupolar Transition in Terbium Palladium Bronze TbPd3S4

Abstract

Specific heat and magnetic susceptibility measurements were performed on single crystalline TbPd 3 S 4 , as well as neutron powder diffraction experiments in various magnetic fields. The sharp peak in the specific heat at the Neel temperature T N = 2.55 K and the discontinuous decrease in the magnetic susceptibility at T N suggested that a first-order antiferromagnetic (AFM) transition was occurring. Field-induced phases were found above about 0.5 T. Since the phase boundary between the field-induced and paramagnetic phases in the B – T phase diagram is of the “re-entrant” type, the field-induced phase can be concluded to be antiferroquadrupolar (AFQ) ordering one. The appearance of a canted magnetic structure above 0.5 T supports the existence of field-induced AFQ ordering. In addition to a magnetic interaction, a quadrupolar or higher multipolar interaction is crucial for determining the magnetic ground state in TbPd 3 S 4 . The first-order-like AFM transition is caused by these multipolar interactions.