Tuning the austenite and martensite phase fraction in ferromagnetic shape memory alloy ribbons of Ni ₄₅Co ₅Mn ₃₈Sn ₁₂

The ferromagnetic shape memory alloy ribbons with composition Ni ₄₅Co ₅Mn ₃₈Sn ₁₂ are shown to have field induced kinetically arrested ferromagnetic austenite phase down to the low temperature due to hindered martensite transformation. This gives rise to the coexisting martensite and austenite phases in a wide range of temperature and field. Here, we show a systematic rise in arrested austenite phase with the reduction in martensite phase quantitatively by various magnetization measurements. The fraction of these coexisting phases can be tuned in "field-temperature" space. Further, we show that the "domain" of tunability varies with temperature.