Giant magnetic coercivity in CaCu₅-type SmNi₃TSi (T=Mn–Cu) solid solutions

The effects of transition metal substitution for Ni on the magnetic properties of the CaCu₅-type SmNi₃TSi (T=Mn, Fe, Co, Cu) solid solutions have been investigated. SmNi₃MnSi, SmNi₃FeSi, SmNi₃CoSi and SmNi₃CuSi show ferromagnetic ordering at 125 K, 190 K, 46 K and 12 K and field induced transitions at 65 K, 110 K, 30 K and 6 K, respectively. The magnetocaloric effects of SmNi₃TSi (T=Mn, Fe, Co, Cu) were calculated in terms of isothermal magnetic entropy change (ΔS_m). The magnetic entropy ΔS_m reaches value of −1.1 J/kg K at 130 K for SmNi₃MnSi, −0.4 J/kg K at 180 K for SmNi₃FeSi, −0.37 J/kg K at 45 K for SmNi₃CoSi and −0.5 J/kg K at 12 K for SmNi₃CuSi in field change of 0–50 kOe around the ferromagnetic ordering temperature. They show positive ΔS_m of +2.4 J/kg K at 30 K for SmNi₃MnSi, −2.6 J/kg K at 65 K for SmNi₃FeSi, +0.73 J/kg K at 15 K for SmNi₃CoSi and −0.5 J/kg K at 6 K for SmNi₃CuSi in field change of 0–50 kOe around the metamagnetic-like transition temperature. Below the field induced transition temperature, SmNi₃TSi (T=Mn, Fe, Co, Cu) exhibits giant magnetic coercivity of 80 kOe at 20 K for SmNi₃MnSi, 87 kOe at 40 K for SmNi₃FeSi, 27 kOe at 20 K for SmNi₃CoSi and 54 kOe at 5 K for SmNi₃CuSi. - Graphical abstract: CaCu₅-type SmNi₃MnSi, SmNi₃FeSi, SmNi₃CoSi and SmNi₃CuSi show ferromagnetic ordering at 125 K, 190 K, 46 K and 12 K and field induced transitions at 65 K, 110 K, 30 K and 6 K, respectively. The magnetic entropy ΔS_m reaches value of −1.1 J/kg K at 130 K for SmNi₃MnSi, −0.4 J/kg K at 180 K for SmNi₃FeSi, −0.37 J/kg K at 45 K for SmNi₃CoSi and −0.5 J/kg K at 12 K for SmNi₃CuSi in field change of 0–50 kOe around the ferromagnetic ordering temperature. They show positive ΔS_m of +2.4 J/kg K at 30 K for SmNi₃MnSi, −2.6 J/kg K at 65 K for SmNi₃FeSi, +0.73 J/kg K at 15 K for SmNi₃CoSi and −0.5 J/kg K at 6 K for SmNi₃CuSi in field change of 0–50 kOe around the metamagnetic-like transition temperature. Below the field induced transition temperature, SmNi₃TSi (T=Mn, Fe, Co, Cu) exhibits giant magnetic coercivity of 80 kOe at 20 K for SmNi₃MnSi, 87 kOe at 40 K for SmNi₃FeSi, 27 kOe at 20 K for SmNi₃CoSi and 54 kOe at 5 K for SmNi₃CuSi. - Highlights: • CaCu₅-type SmNi₃{Mn, Fe, Co, Cu}Si exhibit the Curie points at 12–190 K. • SmNi₃{Mn, Fe, Co, Cu}Si show field induced transition at 6–110 K. • SmNi₃MnSi shows huge magnetic hysteresis with coercive field of 80 kOe at 20 K. • SmNi₃FeSi shows huge magnetic hysteresis with coercive field of 87 kOe at 40 K. • SmNi₃CuSi shows giant coercive field of 54 kOe at 5 K.