Structural, thermo-electric, and thermo-magnetic characteristics of non-stoichiometric L21-type Fe43Mn29Si28 Heusler structures

Abstract

The structural, thermo-electrical, and thermo-magnetic characteristics of non-stoichiometric L21-type Fe43Mn29Si28 Heusler-type alloy, as bulk and glass-coated microwire by employing temperature-dependent electrical resistivity, relative permeability and magnetization measurements. Interestingly, the temperature dependence of electrical resistivity experiments on Fe43Mn29Si28 alloy under a heating-cooling cycle showed a clear temperature hysteresis in the temperature range of 149–226 K, corresponding to the martensitic-austenite phase transformation. During the martensitic transformation, the relative permeability of glass-coated Fe43Mn29Si28 microwire varies significantly by 2350% which much higher than the bulk Fe43Mn29Si28 alloy value of about 940%. Further magnetization experiments on both bulk and glass coated Fe43Mn29Si28 Heusler alloys measured at 0.05 kOe reveal a hysteresis of magnetization during heating and cooling process in the temperature range of 181–194 K attributed to martensitic transformation. Magnetic hysteresis measured at 5 K shows that the bulk Fe43Mn29Si28 alloy coercivity is 44 Oe which is magnetically softer than the glass-coated Fe43Mn29Si28 microwire with Hc = 110 Oe. The observation of martensitic transformation in bulk and glass-coated Fe43Mn29Si28 wire would be useful for developing common actuator and sensing applications.