Anisotropy of the magnetocaloric effect: Example of Mn₅Ge₃

We have investigated the field direction dependence of thermo-magnetic behavior in single crystalline Mn₅Ge₃. The adiabatic temperature change ΔTad in pulsed fields, the isothermal entropy change ΔS_iso calculated from static magnetization measurements, and heat capacity have been determined for fields parallel and perpendicular to the easy magnetic direction [001]. The isothermal magnetization measurements yield, furthermore, the uniaxial anisotropy constants in second and fourth order, K₁ and K₂. We discuss how the anisotropy affects the magneto-caloric effect (MCE) and compare the results to the related compound MnFe₄Si₃, which features an enhanced MCE, too, but instead exhibits strong easy plane anisotropy. Our study reveals the importance of magnetic anisotropy and opens new approaches for optimizing the performance of magnetocaloric materials in applications.