Structural and magnetic behavior of Cr${}_2$Co${}_{(1-x)}$Cr${}_x$Al inverse Heusler alloys

Abstract

We report the structural and magnetic behavior of single phase inverse Heusler alloys Cr${}_2$Co${}_{(1-x)}$Cr${}_x$Al ($x=$ 0, 0.2, 0.4) using x-ray diffraction (XRD), Raman spectroscopy, isothermal magnetization, and magnetic susceptibility measurements. Interestingly, the Rietveld refinement of XRD data with the space group I$\bar{4}m2$ reveal a tetragonal distortion with c/a ratio around 1.38 in these inverse Heusler structures. The bulk compositions have been confirmed by energy dispersive x-ray spectroscopy measurements. The active Raman mode F${}_{2g}$ is observed at 320~cm${}^{-1}$, which confirms the X-type Heusler structure as the A2 and B2 type structures are known to be not Raman active. The area of F${}_{2g}$ mode decreases with Cr concentration, which indicate the origin of this mode due to Co vibrations. The isothermal magnetization data confirm the magnetic moment close to zero ($\le$0.02 ${\mu }_B/f.u.$) at $\approx$70~kOe and negligible coercive field suggest the fully compensated ferrimagnetic nature of these samples. The susceptibility behavior indicates irreversibility between zero-field and field-cooled curves and complex magnetic interactions at low temperatures.

arXiv commentAIP Advances (2020)

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