Magnetocaloric effect in {[Fe(pyrazole)4]2[Nb(CN)8]·4H2O}n{[Fe(pyrazole)4]2[Nb(CN)8]·4H2O}n molecular magnet

• Using the technique of relaxation calorimetry the magnetocaloric effect of a novel molecular magnet is analyzed.
• Temperature dependencies of isothermal magnetic entropy change and adiabatic temperature change are estimated.
• Scaling behavior of the magnetocaloric effect is discussed.

Magnetocaloric effect in {[Fe(pyrazole)4]2[Nb(Cn)8]·4H2O}n{[Fe(pyrazole)4]2[Nb(Cn)8]·4H2O}n molecular magnet is reported. It crystallizes in tetragonal I41/a space group. The compound exhibits a phase transition to a long range magnetically ordered state at Tc≈8.3K. The magnetic entropy change ΔSMΔSM as well as the adiabatic temperature change ΔTadΔTad due to applied field change μ0ΔH=0.1μ0ΔH=0.1, 0.2, 0.5, 1, 2, 5, 9 T as a function of temperature have been determined by the relaxation calorimetry measurements. The maximum value of ΔSMΔSM for μ0ΔH=5T is 4.9 J mol−1 K−1 (4.8 J kg−1 K−1) at 10.3 K. The corresponding maximum value of ΔTadΔTad is 2.0 K at 8.9 K. The temperature dependence of the exponent n   characterizing the field dependence of ΔSMΔSM has been estimated. It attains the value of 0.64 at the transition temperature, which is consistent with the 3D Heisenberg universality class.