Investigations on Cu induced couple-decoupled magneto-structural transition in MnCoGe alloys

Abstract

We have investigated structural, transport, magnetic, and magnetocaloric properties of MnCo1-xCuxGe (x = 0, 0.2, 0.4, 0.6) alloys. The non-magnetic (Cu) atom is doped at the Co site which modifies both the structure and electrical properties. The magneto-structural transition changes the order of transition [1st (AFM-FM) to 2nd (FM-PM)]. Giant MCE is observed similar to RT (307 K) for (x = 0) and it's decreases for doped samples. The change in magnetic entropy (Delta S-M) decreases with Cu doping. Refrigeration Capacity (RC) linearly increases with magnetic field and decreases with Cu doping. The order of transitions are confirmed for x = 0.2, 0.4, 0.6 alloys by the analysis of critical exponents via modified Arrott plots and Kouvel-Fisher method. The Landau coefficients, spontaneous magnetizations and local exponent from isothermal curves are also estimated. The both value of Sommerfeld and Debye coefficients are seen to increas by Cu substitution.