Magnetic-Field-Controlled Twin Boundaries Motion and Giant Magneto-Mechanical Effects in Ni-Mn-Ga Shape Memory Alloy

摘要

Recently, several research groups have reported on the observation ofsuper-large more than 5% magneto-strain effect in some non-stoichiometricNi-Mn-Ga alloys close to 5.78% value expected from the tetragonality aspectratio of the martensite crystal lattice. New Ni-Mn-Ga alloys showing giantmagneto-strain effect display simultaneously few interesting physical effectsand new behavior for some magnetic and mechanical properties which is verydifferent from that earlier observed in Ni-Mn-Ga showing lower magneto-straineffect. This report represents some new experimental results and thequantitative model describing large magneto-strain effect and main mechanicaland magnetic properties observed in several ferromagnetic shape-memory alloys.The model application to giant magneto-strain effect recently found in somenon-stoichiometric Ni-Mn-Ga alloys is discussed.