Effects of the Mn/Co ratio on the magnetic transition and magnetocaloric properties of Mn_1+xCo_1-xGe alloys

We have investigated the magnetic transition and magnetocaloric effects of Mn_1+xCo_1-xGe alloys by tuning the ratio of Mn/Co. With increasing Mn content, a series of first-order magnetostructural transitions from ferromagnetic to paramagnetic states with large changes of magnetization are observed at room temperature. Further increasing the content of Mn (x=0.11) gives rise to a single second-order magnetic transition. Interestingly, large low-field magnetic entropy changes with almost zero magnetic hysteresis are observed in these alloys. The effects of Mn/Co ratio on magnetic transition and magnetocaloric effects are discussed in this paper.