Impact of hydrogen absorption on crystal structure and magnetic properties of geometrically frustrated Nd2Ni2In

Nd2Ni2In orders antiferromagnetically at TN = 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 〈1 1 0〉 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≈7 achieved through the sequence of intermediate hydrides. The highest hydride has an orthorhombic distortion and volume expansion exceeding 23%. It is antiferromagnetic below TN ≈ 3 K.