Pressure-induced changes in the structural and magnetic properties of YFe2D4.2

Abstract

The study of the structural and magnetic properties of YFe 2D4.2 under high pressure has been performed by combining energy dispersive x-ray diffraction at room temperature up to 5.5 GPa, neutron diffraction studies at low temperature up to 2.5 GPa, and magnetization measurements up to 1 GPa. The monoclinic structure of YFe2D 4.2 at ambient temperature and pressure is related to a distortion of the initial cubic C15 structure of YFe2 by the ordering of inserted D atoms. A structural transition from monoclinic to cubic structure is observed at 4 GPa. The high pressure cubic YFe2D4.2 has a 19% higher cell volume than that of YFe2. The application of an external pressure leads to the progressive decrease of the transition temperature T M0 from ferro to antiferromagnetic order (T M0 = 84 K at ambient pressure) and even to the suppression of the ferromagnetic ground state for pressures larger than 0.54 GPa. Moreover using the compressibility value determined by x-ray diffraction (κ = 0.013 GPa-1), the decrease of volume at the critical pressure of 0.54 GPa (0.70%) is in very good agreement with the increase of volume observed at the transition from antiferromagnetic to ferromagnetic state at ambient pressure (0.65%), indicating the crucial role of volume effect. An antiferromagnetic structure was detected between TM0 and TN and for pressures larger than 0.54 GPa in the whole temperature range below T N. In addition, a large pressure effect on the spontaneous magnetization MS for pressures below 0.4 GPa, d ln MS/d P = -7.3 × 10-2 GPa-1 was discovered. This clearly proves the delocalized character of the iron 3d band magnetism in YFe 2D4.2 compound. The pressure evolution of the magnetic phase diagram of YFe2D4.2 has been determined. © 2011 American Physical Society.