Impact of hydrogen absorption on crystal structure and magnetic properties of geometrically frustrated Nd2Ni2In
Abstract
Nd2Ni2In orders antiferromagnetically at T-N = 8 K. A possible first-order type of the phase transition can be related to the frustrated lattice of the Shastry-Sutherland type.
The transition does not shift in magnetic field but turns into a ferromagnetic transition in magnetic fields exceeding 0.3 T. Powder neutron diffraction determined the magnetic structure with Nd moments oriented mutually perpendicular along the directions of the type.
Large change of magnetic entropy in weak magnetic fields leads to a giant magnetocaloric effect. Reversible hydrogen absorption in pressures of several bar leads to the hydride Nd2Ni2InH approximate to 7 achieved through the sequence of intermediate hydrides.
The highest hydride has an orthorhombic distortion and volume expansion exceeding 23%. It is antiferromagnetic below T-N approximate to 3 K.