Coexisting structural disorder and robust spin-polarization in half-metallic FeMnVAl

Abstract

Half-metallic ferromagnets (HMF) are on one of the most promising materials in the field of spintronics due to their unique band structure consisting of one spin sub-band having metallic characteristics along with another sub-band with semiconductor-like behavior. In this work, we report the synthesis of a novel quaternary Heusler alloy FeMnVAl and have studied the structural, magnetic, transport, and electronic properties complemented with first-principles calculations. Among different possible structurally ordered arrangements, the optimal structure is identified by theoretical energy minimization. The corresponding spin-polarized band structure calculations indicates the presence of a half-metallic ferromagnetic ground state. A detailed and careful investigation of the x-ray diffraction data, Mössbauer and nuclear magnetic resonance spectra suggest the presence of site-disorder between the Fe and Mn atoms in the stable ordered structure of the system. The magnetic susceptibility measurement clearly establishes a ferromagnetic-like transition below $\sim$213 K. The ${}^{57}$Fe Mössbauer spectrometry measurements suggest only the Mn-spins could be responsible for the magnetic order, which is consistent with our theoretical calculation. Surprisingly, the density-functional-theory calculations reveal that the spin-polarization value is almost immunized (92.4\% $\to$ 90.4\%) from the Mn-Fe structural disorder, even when nonmagnetic Fe and moment carrying Mn sites are entangled inseparably. Robustness of spin polarization and half metallicity in the studied FeMnVAl compound comprising structural disorder is thus quite interesting and could provide a new direction to investigate and understand the exact role of disorders on spin polarization in these class of materials, over the available knowledge.

arXiv comment12 pages

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Cited by in corpus (8)

• Experimental observation of spin glass state in highly disordered quaternary Heusler alloy FeRuMnGa
• Rare observation of spin-gapless semiconducting characteristics and related band topology of quaternary Heusler alloy CoFeMnSn
• High spin-polarization in a disordered novel quaternary Heusler alloy FeMnVGa
• 4d-element induced improvement of structural disorder and development of weakly re-entrant spin-glass behaviour in NiRuMnSn
• Al${}_2$MnCu: A magnetically ordered member of the Heusler alloy family despite having a valence electron count of 24
• Restructuring disorder: Transformation from the antiferromagnetic order in Fe2VSi to the ferromagnetic state in FeRuVSi by substitution of a non-magnetic element
• Disproportionate influence of site disorder on the evolution of magnetic phases in anti-Heusler alloy Al${}_2$MnFe
• Randomness in atomic disorder and consequent squandering of spin-polarization in a ferromagnetically fragile quaternary Heusler alloy FeRuCrSi