Transition temperature tuning of Ni2FeGa based Heusler alloys in form of glass-coated microwires

Abstract

We report on the possibility of tuning the martensitic transition temperature in Ni2FeGa Heusler alloys prepared in the form of glass coated microwires. Glass-coated microwires with different valence electron concentration (e/a) and possible structural transformation in the temperature range from 100 K to 400 K have been prepared (Ni51+xFe22-xGa27; x = 0, 2, 4). Magnetic and electrical resistance measurements demonstrated a linear dependence of structural transformation temperature on valence electron concentration TT(e/a). In order to prove the correctness of the TT(e/a) dependence, a glass-coated microwire with the transformation temperature 310 K (human body temperature) was selected, prepared and experimentally investigated. The effect on magnetocaloric response is also shown. Our theoretical prediction together with the experimental results point to the fact that the e/a parameter is the key parameter for transition temperature tuning in Ni2FeGa Heusler-based glass-coated microwires.