Giant antiferromagnetic negative thermal expansion in (MnNiGe)1-x(MnCoSn)x compounds

Abstract

The large volumetric contraction effect presented by MnM’X (M’ = Co, Ni; X = Ge, Si) during the martensitic (MA) transformation displays their potential applications in negative thermal expansion (NTE) field. In this work, we report the giant antiferromagnetic (AFM) NTE in (MnNiGe)1-x(MnCoSn)x (0.02 ≤ x ≤ 0.1) compounds. When x = 0.02, 0.04, 0.06 and 0.1, their average linear NTE coefficients reach −48 ppm/K (220 K - 332 K), −96 ppm/K (174 K-280 K), −92 ppm/K (116 K-220 K) and −35 ppm/K (75 K-130 K), respectively. Moreover, the magnetization shows a descending tendency with increasing x from 0.02 to 0.1, which can be attributed to the more-antiparallel AFM ground state, suggesting their feasible applications in the magnetic environment.