Magneto-structural transition in intermetallic alloys and compounds
Abstract:First order magneto-structural transition occurs when there is a concomitant change in the magnetic and structural properties of a solid material under the variation of various external parameters such as temperature, pressure or magnetic field. It plays a pivotal role towards the functional properties of various materials of current interest including CMR manganites, rare-earth intermetallics, magnetic shape memory alloys and so on. The off-stoichiometric Ni-Mn-Z (Z = In, Sn, Sb) based ferromagnetic Heusler compositions have recently attracted considerable attraction for their novel magneto-functional properties which include giant field induced strain (magnetic super- lasticity), large inverse magnetocaloric effect, baro-caloric effect giant magneto-resistance, exchange bias effect. The root of their magneto-functional properties is related to the thermally driven martensitic type structural transition, which is quite susceptible to the applied magnetic field. Due to the presence of first order structural transition in an otherwise ferromagnetically ordered state, the overall behavior of these compositions are found to be quite complex and a purely ferromagnetic ground state is inadequate for the descriptionof various magnetic properties of the alloys. The present talk will cover some fascinating properties of these Heusler based alloys focusing both fundamental and functional aspects.