The Supercell Scaling Investigation of Magnetic Properties in Ni-Mn-X (X=Ga, In, Sn, Sb) Heusler Alloys by Means of Firs
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The Supercell Scaling Investigation of Magnetic Properties in Ni-Mn-X (X=Ga, In, Sn, Sb) Heusler Alloys by Means of First-principles Methods Vasiliy Buchelnikov1, Vladimir Sokolovskiy1,2, Mikhail Zagrebin1, Sergey Taskaev1, Vladimir Khovaylo2, Peter Entel3 1
Condensed Matter Physics Department, Chelyabinsk State University, Chelyabinsk, 454001,
Russian Federation. 2
National University of Science and Technology “MISiS”, Moscow, 119049, Russian
Federation. 3
Faculty of Physics and Center for Nanointegration, CENIDE, University of Duisburg-Essen,
Duisburg, 47048, Germany. ABSTRACT In this work we study the influence of supercell scaling on magnetic properties in Ni-Mn-XZ alloys by means of ab initio calculations with the help of Quantum Espresso PWSCF package and the spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) code based on DFT approximation. It is shown that the supercell calculations for the equilibrium lattice parameter are coincided with the calculations for simple primitive lattice. The exchange parameters for NiMn-X alloys obtained from supercell calculations are large than calculated for simple primitive lattice. INTRODUCTION Magnetic shape memory alloys are being widely explored for many technological applications. Typical representatives of this class of materials are intermetallic Ni-Mn-X (X = Ga, In, Sn, Sb) Heusler alloys. The Heusler alloys have been experimentally studied quite extensively for their magnetocaloric and magnetomechanical properties and for their applications [1-3]. These compounds crystallize in the cubic structure (Fm-3m, space group no. 225) with Cu2MnAl (L21) as prototype. The Ni atoms form a primitive cubic sublattice and adjacent cubes of this Ni sublattice are filled alternating by Mn and X. The primitive cell of L21 structure contains four atoms that from the base of the face-centered cubic primitive cell. The result is a lattice with the Fm-3m symmetry where the Wyckoff positions 4a (0, 0, 0), 4b (1/2, 1/2, 1/2), and 8c (1/4, 1/4, 1/4) are occupied by X, Mn, and Ni atoms, respectively. From theoretical point of view, the stoichiometric Ni2MnX and off-stoichiometric Ni2+xMn1-xX or Ni2Mn1+xX1-x have been investigated in several papers with the use of ab initio calculations [4-6]. For those alloys the exchange magnetic couplings were calculated with the primitive cell of austenite and martensite. All calculations have shown a strong competitive behavior between the ferromagnetic and antiferromagnetic order. In this work we study the influence of supercell scaling on magnetic properties in Ni-Mn-XZ alloys by means of ab initio calculations with help of Quantum Espresso PWSCF package and
the spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) code based on DFT approximation [7-9]. THEORETICAL DETAILS AND RESULTS First we check the influence of supercell scaling on equilibrium lattice parameter on example of PtNiMnGa quaternary Heusler alloys. For relaxation of the lattice we used the Quantum Espresso PWSCF package [7]. The generalized gradient approxima
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