Phase Transitions and Magnetocaloric Properties in MnCo _1-x Zr _x Ge Compounds

The structural, magnetic, and magnetocaloric properties of MnC o 1 - x Z r x Ge (0.01 ≤ x ≤ 0.04) have been studied through X-ray diffraction, differential scanning calorimetry, and magnetization measurements. Results indicate that the partial substitution of Zr for Co in MnC o 1 - x Z r x Ge decreases the martensitic transition temperature (T M). For x = 0.02, T M was found to coincide with the ferromagnetic transition temperature (T C) resulting in a first-order magnetostructural transition (MST). A further increase in zirconium concentration (x = 0.04) showed a single transition at T C . The MST from the paramagnetic to ferromagnetic state results in magnetic entropy changes (- Δ S M) of 7.2 J/kgK for Δ H = 5 T at 274 K for x = 0.02. The corresponding value of the relative cooling power (RCP) was found to be 266 J/kg for Δ H = 5 T. Thus, the observed large value of MCE and RCP makes this system a promising material for magnetic cooling applications.