Half-metallicity versus Symmetry in Pt, Ni and Co-based Half Heusler Alloys: A First-principles Calculation

Abstract

Using first principles calculations based on density functional theory, we study the geometric, electronic, and magnetic properties of Pt, Ni and Co-based half Heusler alloys, namely, Pt$BC$, Ni$BC$ and Co$BC$ ($B$ = Cr, Mn and Fe; $C$ = Al, Si, P, S, Ga, Ge, As, Se, In, Sn, Sb and Te). We calculate the formation energy of these alloys in various crystal symmetries, which include, the (face-centered) cubic $C{1}_b$ ($F\bar{4}$3m), orthorhombic ($Pnma$), as well as hexagonal ($P\bar{6}2m$ and $P{6}_3/mmc$) structures. It has been observed that out of all the 108 structures, studied here, energetically stable cubic structure is observed for only 18 materials. These alloys are primarily having either a $C$ atom or an $A$ atom with a high atomic number. We also observe that along with the alloys with $C$ atoms from group IIIA, IVA and VA -- alloys with $C$ atoms from group VIA are also found to be, by and large, energetically stable. To examine the relative stabilities of different symmetries in order to search for the respective lowest energy state for each of the above-mentioned systems, as well as to find whether a material in the ground state is half-metallic or not, we analyze the formation energy, and the electronic density of states, in detail. Based on these analyses, the possibility of existence of any {\it one-to-one relationship} between the {\it cubic symmetry} and the {\it half-metallicity} in these half Heusler alloys is probed. Subsequently, we predict about the existence of a few new {\it non-cubic} half Heusler alloys with substantially low density of states at one of the spin channels and reasonably {\it high spin polarization at the Fermi level}

References in corpus (11)

• Spintronics: Fundamentals and applications
• Origin and Properties of the Gap in the Half-Ferromagnetic Heusler Alloys
• Computational Investigation of Half-Heusler Compounds for Spintronics Applications
• First-principles investigation of half-metallic ferromagnetism of half-Heusler compounds XYZ
• Probing the possibility of coexistence of martensite transition and half-metallicity in Ni and Co-based full Heusler Alloys : An ab initio Calculation
• Above-room-temperature ferromagnetism in half-metallic Heusler compounds NiCrP, NiCrSe, NiCrTe and NiVAs: A first-principles study
• Ab-initio determined electronic and magnetic properties of half-metallic NiCrSi and NiMnSi Heusler alloys; the role of interfaces and defects
• New High-$T_c$ Half-Heusler Ferromagnets NiMnZ (Z = Si, P, Ge, As)
• Ab initio Studies on Electronic and Magnetic Properties of X${}_2$PtGa (X = Cr, Mn, Fe, Co) Heusler Alloys
• Structural and magnetic properties of half-heusler alloys NiCrZ (Z = Si, P, Ge, As, Te): First principle study
• Presence of atomic disorder and its effect on magnetic and electronic properties of NiCrGa half Heusler alloy

Cited by in corpus (2)

• Effect of L21 and XA ordering on phase stability, half-metallicity and magnetism of Co2FeAl Heusler Alloy: GGA and GGA+U approach
• Ab initio Prediction of Mechanical, Electronic, Magnetic and Transport Properties of Bulk and Heterostructure of a Novel Fe-Cr based Full Heusler Chalcogenide