Speaker
Description
Magnetic Heusler alloys, which undergo a martensitic-like structural transition, display interesting functional properties. Regarding the synthesis of these alloys, most of the work conducted up to now has focused on bulk and ribbon samples prepared using conventional melting and melt-spinning techniques. This work reports the microstructure, structural, magnetic, and magnetocaloric characteristics of polycrystalline glass-coated Ni$_{50}$Mn$_{37}$Sb$_{13}$ microwires obtained by the Taylor-Ulitovsky technique. The results are compared with those obtained for a bulk alloy of the same composition. The microwires exhibited a remarkably uniform diameter, averaging around 200 microns. Elemental chemical composition analyses reveal slight deviations in the Mn and Sb content from the nominal values. At room temperature, austenite shows an L2$_1$-type cubic crystal structure (space group Fm-3m) and undergoes a second-order magnetic phase transition with a Curie temperature ($T_C^A$) of 332 K. The thermomagnetic curve measured under a field of 5 mT in the temperature range from 150 K to 400 K shows the occurrence of a broad first-order martensitic-like phase transition at a temperature of around 233 K. One notable room temperature magnetic characteristic of these samples is their ability to achieve saturation magnetization at a low magnetic field strength of around 0.15 T. For a magnetic field change of 2 T, the produced microwires show a maximum magnetic entropy change $|\Delta SM|_{max}$ of 1.2 Jkg$^{-1}$K$^{-1}$ at the second-order transition of austenite.
Acknowledgements
Work supported by Laboratorio Nacional de Investigaciones en Nanociencias y Nanotecnología (LINAN, IPICyT), CONAHCYT, Mexico (research project CF-2023-I-2143), The Slovak Grant Agency APVV-160079 grant and VEGA 1/0180/23. M. López-Cruz thanks CONAHCYT and SAIA for supporting his Ph.D. studies at IPICyT (scholarship 831827) and his stay at UPJS, Slovakia. The technical support received from Dr. I.G. Becerril Juárez is acknowledged.
