Magnetic field-controlled two-way shape memory in CoNiGa single crystals

Abstract

A two-way magnetic field controlled shape memory effect has been observed in single crystals of CoNiGa with martensitic transformation temperature ranging from 205 to 341 K. Two-way shape memory with −2.3% strain has been obtained in free samples. By applying a bias field of up to 2 T, the shape memory strain can be continuously controlled from negative 2.3% to positive 2.2% giving it a total strain of 4.5%. The magnetic properties of CoNiGa show that it is a good shape memory material working at relatively high temperature of up to 450 K, and has a lower magnetic anisotropy than NiMnGa.