The effect of pressure and alloying on half-metallicity of quaternary Heusler compounds CoMnYZ (Z = Al, Ga, and In) Cover

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The effect of pressure and alloying on half-metallicity of quaternary Heusler compounds CoMnYZ (Z = Al, Ga, and In)

Materials Science-Poland

Volume 34 (2016): Issue 4 (December 2016)

By: M. Rahmoune, A. Chahed, A. Amar, H. Rozale, A. Lakdja, O. Benhelal and A. Sayede

Open Access

|Dec 2016

Figures & Tables

Total energy as a function of volume per formula unit (f.u.) in the three atomic arrangements: type 1, type 2 and type 3 for the CoMnYZ (Z = Al, Ga, and In) compounds. The curves correspond to the FM state.

Total energy as a function of volume per formula unit (f.u.) in the three magnetic states FM, AFM and NM for the CoMnYZ (Z = Al, Ga, and In) compounds. The curves correspond to the type 1 structure.

Spin polarized band structure of CoMnYZ (Z = Al, Ga and In) at their equilibrium lattice constant. The red lines correspond to the majority spin bands (minority spin bands).

Spin-polarized total and partial densities of states (DOS) of CoMnYAl.

Spin-polarized total and partial densities of states (DOS) of CoMnYGa.

Spin-polarized total and partial densities of states (DOS) of CoMnYIn.

Schematic illustration of the origin of the gap in the minority band in CoMnYZ alloy: d1, d2, d3, d4 and d5 denote the dxy, dyx, dzx, dz2, dx2− y2 orbitals, respectively.

Dependence of the HM state on the lattice constant (uniform strain) (a) and at the c/a ratio (tetragonal distortion) (b) of CoMnYZ (Z = Al, Ga, and In). The blue lines correspond to the valence bands maxima and the red lines correspond to the conduction band minima in the minority spin states (spin-down states).

The variation of the lattice parameter with concentration x of CoMnYGa1−xAlx, CoMnYGa1−xInx and CoMnYAl1−xInx Heusler alloys (dotted line is the linear fit).

Variation of the band gap Eg and half-metallic gap EHM with concentration x of CoMnYGa1−xAlx, CoMnYGa1−xInx and CoMnYAl1−xInx Heusler alloys (dotted line is the linear fit).

Variation of Curie temperature with concentration x of CoMnYAl1−xGax, CoMnYGa1−xInx and CoMnYAl1−xInx Heusler alloys (dotted line is the linear fit).

Semiconducting gap Eg, half-metallic gap EHM, total magnetic moment μtot and Curie temperature Tc of CoMnYAl1−x Inx alloys_

x	a	E_g	E_HM	μ_tot	T_c
	[Å]	[eV]	[eV]	[μ_B]	[K]
0	6.412	0.51	0.158	4	482
0.25	6.4652	0.43684	0.0993	4	610
0.5	6.5161	0.44	0.11	4	690
0.75	6.5641	0.4685	0.13	4	738
1	6.613	0.54	0.195	4	805

Semiconducting gap Eg, half-metallic gap EHM, total magnetic moment μtot, magnetic moment per atom (Co, Mn, Y, Al, Ga, In), magnetic moment in the interstitial region μint in CoMnYAl, CoMnYGa and CoMnYIn compounds_

Compound	E_g [eV]	E_HM [eV]	μ_tot [μB]	μCo	μMn	μY	μX	μ_int
CoMnYAl	0.51	0.158	4	0.827	3.5	−0.108	μ0.08	μ0.139
CoMnYGa	0.59	0.294	4	0.8	3.555	μ0.111	μ0.072	μ0.09
CoMnYIn	0.54	0.195	4	0.75	3.6	μ0.137	μ0.058	μ0.16

Semiconducting gap Eg, half-metallic gap EHM, total magnetic moment μtot and Curie temperature Tc of CoMnYGa1−x Inx alloys_

x	a	E_g	E_HM	μ_tot	T_c
	[Å]	[eV]	[eV]	[μ_B]	[K]
0	6.387	0.59	0.294	4	616
0.25	6.4403	0.54	0.23	4	690
0.5	6.497	0.5231	0.2	4	757
0.75	6.5508	0.505	0.18	4	774
1	6.613	0.54	0.195	4	805

Calculated total energies Etot per formula unit, equilibrium lattice constant a0, bulk modulus B and formation energy Ef for CoMnYZ (Z = Al, Ga, In) compounds in their different structure types and magnetic configurations_

Compound Structure		E_tot [Ry]			a₀ [Å]	B₀ [GPa]	E_f [Ry])
		NM	FM	AFM	FM	FM	FM
CoMnYAl	Type 1	−12361.325192	−12361.373842	−12361.353614	6.412	100.212	−1.294
	Type 2	−12361.227488	−12361.323233	−12361.280855	6.453	95.178	−1.243
	Type 3	−12361.325135	−12361.369712	−12361.342789	6.422	102.798	−1.288
CoMnYGa	Type 1	−15763.903474	−15763.961374	−15763.925582	6.387	95.621	−1.228
	Type 2	−15763.831806	−15763.934409	−15763.854632	6.436	93.368	−1.142
	Type 3	−15763.903455	−15763.949612	−15763.925582	6.389	98.016	−1.189
CoMnYIn	Type 1	−23642.224948	−23642.301847	−23642.237173	6.613	92.844	−1.168
	Type 2	−23642.137606	−23642.251825	−23642.185687	6.672	83.238	−1.101
	Type 3	−23642.225186	−23642.275945	−23642.275869	6.609	94.409	−1.148

Semiconducting gap Eg, half-metallic gap EHM, total magnetic moment μtot and Curie temperature Tc of CoMnYGa1−xAlx alloys_

x	a	E_g	E_HM	μ_tot	T_c
	[Å]	[eV]	[eV]	[μ_B]	[K]
0	6.387	0.59	0.294	4	616
0.25	6.3909	0.4886	0.176	4	593
0.5	6.3965	0.4763	0.157	4	553
0.75	6.4034	0.4693	0.14234	4	514
1	6.412	0.51	0.158	4	482

DOI: https://doi.org/10.1515/msp-2016-0120 | Journal eISSN: 2083-134X | Journal ISSN: 2083-1331

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Language: English

Page range: 905 - 915

Submitted on: May 24, 2016

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Accepted on: Oct 19, 2016

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Published on: Dec 19, 2016

Published by: Wroclaw University of Science and Technology

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

density functional theory,

quaternary Heusler compounds,

half-metallic ferromagnetic,

Related subjects:

Materials sciences,

Materials sciences, other,

Functional and smart materials,

Materials characterization and properties

© 2016 M. Rahmoune, A. Chahed, A. Amar, H. Rozale, A. Lakdja, O. Benhelal, A. Sayede, published by Wroclaw University of Science and Technology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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