Temperature dependence of single twin boundary motion in Ni-Mn-Ga martensite

Magnetic-field-induced reorientation in Ni-Mn-Ga five-layered martensite (10 M) mediated by the motion of single twin boundary was evaluated from magnetization measurements between 20 and 300 K. At 300 K, the single twin boundary moved in an exceptionally small field of 25 kA/m. Twinning stress, as a measure of the twin boundary mobility, was determined from the magnetization curves using a magnetic-energy-based model; it increased from approximate to 0.1 MPa at 300 K to approximate to 0.8 MPa at 20 K. The dependence is discussed in terms of thermal activation and the effect of intermartensitic transformation is considered. (C) 2011 American Institute of Physics. [doi:10.1063/1.3573860]