In situobservation of the magnetocaloric effect through neutron diffraction in the Tb(DCO2)3and TbODCO3frameworks

Abstract

Probing the magnetic structure of magnetocaloric materials in applied fields, can reveal detailed insight into the mechanism of magnetic refrigeration thereby linking the magnetic states that form under applied magnetic fields to changes in magnetic entropy. This study probes the long range magnetic order in Tb(DCO2)3and TbODCO3as a function of temperature and applied magnetic field, through neutron diffraction measurements. A triangular Ising antiferromagnetic phase is formed, in small applied magnetic fields in Tb(DCO2)3, a spin flip transition occurs to a simple ferromagnetic structure in higher applied fields. TbODCO3undergoes a phase transition, in applied fields, into two magnetic phases; namely a buckled chain ferromagnetic phase along theb-axis and a canted antiferromagnetic phase, with a ferromagnetic component alongc-axis. Both of the states observed in TbODCO3are consistent with Ising-like anisotropy previously reported in TbODCO3and the coexistance of these is likely the result of applying a magnetic field to a powdered sample.