Magnetization rotation and rearrangement of martensite variants in ferromagnetic shape memory alloys

It is widely recognized that the rearrangement of martensite variants in a ferromagnetic shape memory alloy (FSMA) can lead to much higher strain than conventional magnetostriction. In this letter, the authors show that magnetization rotation can reduce ferromagnetic shape memory effect substantially when motion of the interface is severely hindered under a relatively large applied stress. This limits the energy density of FSMA actuators and suggests that hard magnetic anisotropy is necessary to achieve large actuation force. The analysis agrees well with experiments. (c) 2007 American Institute of Physics.