Magnetic properties of the off-stoichiometric GdNi2Mnx alloys

Abstract The structure and magnetic properties of the off-stoichiometric GdNi 2 Mn x (0 ⩽  x  ⩽ 0.6) alloys have been studied. The alloys with 0  х 2 -type, whereas, starting from the composition х  ⩾ 0.4, in the samples there forms the PuNi 3 -type phase. Increase in the Mn content is found to lead to a considerable growth of the Curie temperature from 80 K for the binary GdNi 2 up to 190 K for the GdNi 2 Mn 0.4 alloy. Magnetization at 4 K decreases with increasing x , which indicates the formation of a ferrimagnetic structure. The magnetic entropy change has been determined from the temperature dependences of the magnetization using the Maxwell equation. For GdNi 2 Mn 0.4 , upon changing the magnetic field from 0 to 9 T, the isothermal entropy change in the vicinity of the Curie temperature has been found to be 4.6 J kg −1  K −1 . The results are discussed under assumption of growth of both the Ni magnetic moment and Gd–Mn and Ni–Mn exchange interactions with increasing the manganese content.