Disproportionate influence of site disorder on the evolution of magnetic phases in anti-Heusler alloy Al${}_2$MnFe

Abstract

Anti-Heusler alloys, being a new addition to the Heusler alloys family, exhibit atomic disorders, and almost all of them are reported as a re-entrant spin-glass system. Although such spin-glass feature is generally attributed to the inherent atomic disorder, a comprehensive and extensive investigation on the individual roles of different types of disorders in magnetic interactions remains lacking for any of the reported anti-Heusler systems. As an illustrative case, we have carried out an in-depth experimental as well as theoretical investigation of structural, magnetic, and transport properties of a polycrystalline anti-Heusler alloy, Al${}_2$MnFe. While the major atomic disorder is found to be among Fe and Mn atoms, which are randomly distributed among the two octahedral sites, 4$a$ and 4$b$ (B2-type disorder), a relatively small fraction ($\sim$12\%) of Mn atoms also replace Al atoms at the tetrahedral 8$c$ site. Magnetically, the system undergoes two transitions: a paramagnetic to a ferromagnetic transition at $T_{\mathrm{C}}\sim$113~K, followed by a spin-glass phase transition below $T_{\mathrm{f}}\sim$20~K. Here, the magnetic moment is primarily confined to Mn atoms. Very interestingly, our theoretical analysis reveals that the ferromagnetic spin arrangement remains rather robust in spite of the 50\% disorder of moment-carrying Mn atoms between the two octahedral sites, but a much smaller ($\sim$12\%) cross-distribution of Mn atoms between octahedral and tetrahedral sites are sufficient to impose a reentrant spin-glass state at low temperature. Our analysis brings forth the importance of understanding the role of individual types of swap-disorder on magnetic properties in the anti-Heusler family of materials.

References in corpus (15)

• Ferromagnetic cluster spin-glass behavior in PrRhSn3
• Half-Metallic Ferromagnetism in the Heusler Compound Co${}_2$FeSi revealed by Resistivity, Magnetoresistance, and Anomalous Hall Effect measurements
• A.C. susceptibility as a probe of low-frequency magnetic dynamics
• Large Noncollinearity and Spin Reorientation in the Novel Mn2RhSn Heusler Magnet
• Theoretical prediction and experimental study of a ferromagnetic shape memory alloy: Ga_2MnNi
• Memory effects and magnetic relaxation in single-crystalline La${}_{0.9}$Sr${}_{0.1}$CoO${}_3$
• Anti-site disorder and Berry curvature driven anomalous Hall effect in spin gapless semiconducting Mn2CoAl Heusler compound
• Coexisting structural disorder and robust spin-polarization in half-metallic FeMnVAl
• Experimental observation of spin glass state in highly disordered quaternary Heusler alloy FeRuMnGa
• Effect of Fe and Co substitution on martensitic stability, elastic, electronic and magnetic properties of Mn${}_2$NiGa: insights from \textit{ab initio} calculations
• High spin-polarization in a disordered novel quaternary Heusler alloy FeMnVGa
• Influence of structural disorder on magnetic properties and electronic structure of YCo${}_2$
• 4d-element induced improvement of structural disorder and development of weakly re-entrant spin-glass behaviour in NiRuMnSn
• Does carrier localization affect the anomalous Hall effect?
• Al${}_2$MnCu: A magnetically ordered member of the Heusler alloy family despite having a valence electron count of 24