Magnetocaloric Measurements on Dysprosium Phosphate (DyPO4)

Abstract

DyPO4 orders below 3.39 K as a two-sublattice Ising antiferromagnet with its moments along the crystallographic c-axis. Measurements of the specific heat and the magnetocaloric effect with the magnetic field applied along c are performed to determine the phase diagram. A new intermediate ferrimagnetic phase is found at the metamagnetic transition from the antiferromagnetic to the paramagnetic state below 0.82 K. Although this phase extends only over a field range of about 20 mT, it is clearly seen since for crystals with finite demagnetising factor it produces additional mixed phases at the first-order phase boundary. The measured phase diagram is verified by mean-field calculations and the possibility of even more ferrimagnetic phases is discussed.