Large Negative Thermal Expansion and Magnetoelastic Coupling in Metamagnetic Tetragonal (Mn, T)2Sb (T = Cr, V) Alloys

Abstract

Metamagnetic phase transition of Mn2-xCrxSb (x = 0.07, 0.09, and 0.11) and Mn2-yVySb (y = 0.1, 0.15) alloys had been studied. More Cr and V substitutions lead into increased phase transition temperature, which is confirmed by differential scanning calorimetry (DSC) measurement. The maximized saturation magnetostriction (λs//) of − 1350 ppm and − 610 ppm under 7 T have been realized in Mn1.93Cr0.07Sb alloy and Mn1.9V0.1Sb alloy, respectively, and gradually decreased with more substitution. Giant negative thermal expansion (NTE) is triggered by metamagnetism. The highest linear coefficient of − 42.4 ppm/K is obtained in Mn1.93Cr0.07Sb alloy, but almost zero expansion is obtained in Mn1.85V0.15Sb alloy. The coincident highest ΔSmax associated with the maximized λs// in both Mn2-xCrxSb (x = 0.07, 0.09, and 0.11) and Mn2-yVySb (y = 0.1, 0.15) systems suggests that the strong magnetoelastic coupling is also beneficial to enhance the magnetic entropy change.