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Emergent properties in the natural composite Ni2MnSb0.5Al0.5.

Authors :: Samanta, Tamalika
Salas, D
Srihari, V
Karaman, I
Bhobe, P A
Source :: Journal of Physics D: Applied Physics; 5/27/2020, Vol. 53 Issue 22, p1-12, 12p
Publication Year :: 2020
Abstract: We have investigated the structure, transport and magnetic properties of Ni<subscript>2</subscript>MnSb<subscript>0.5</subscript>Al<subscript>0.5</subscript> Heusler alloy. Structural analysis using x-ray diffraction and scanning electron microscopy has confirmed Ni<subscript>2</subscript>MnSb<subscript>0.5</subscript>Al<subscript>0.5</subscript> to be a natural composite of Ni<subscript>2</subscript>MnSb and Ni<subscript>2</subscript>MnAl phases, regardless of annealing conditions. This composite has a dendritic microstructure formed by the phase separation during solidification. The electronic phase separation was confirmed using x-ray near edge absorption spectroscopy, recorded at Mn and Ni K-edge and supported by ab-initio calculations of the same using multiple scattering theory. A thorough characterization of this novel composite form of Ni<subscript>2</subscript>MnSb<subscript>0.5</subscript>Al<subscript>0.5</subscript> Heusler alloy has been carried out by recording its magnetic and transport properties including electrical resistivity, thermal conductivity, and heat capacity. The composite micro-structure of this system plays a crucial role in drastically reducing its thermal conductivity value, while maintaining its metallic character. Unlike many oxide composites, the magnetic properties of the Ni<subscript>2</subscript>MnSb<subscript>0.5</subscript>Al<subscript>0.5</subscript> cannot be considered as the volume average of the characteristics of the two phases, rather it shows a long range ferromagnetic order with Curie temperature of 334 K and magnetic moment of 2.52 /f.u. [ABSTRACT FROM AUTHOR]