New quaternary half-metallic ferromagnets with large Curie temperatures

Kundu, Ashis; Ghosh, Srikrishna; Banerjee, Rabin; Ghosh, Subhradip; Sanyal, Biplab

doi:10.1038/s41598-017-01782-5

Cited by 135 publications

(101 citation statements)

References 49 publications

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“…The compound CoMnYAl has total moment 4

μ_{B} / f . u .

with N V = 22, thus follows M =

| N_{normalV} - 18 |

rule. Qualitatively, this is similar to the trends for CoX′Y′Si series . However, only seven compounds from the present study, CoYMnAl, CoZrMnAl, CoRuMnAl, CoRhFeAl, CoPdMnAl, CoNbFeAl, and CoTcFeAl have either integer or near‐integer magnetic moments and thus, are potential half‐metals.…”

Section: Resultssupporting

confidence: 87%

“…Only CoRuMnAl can be considered a near half‐metal as the spin polarization is 94%. Qualitatively this is distinctly different from the Si‐series quaternary compounds where two half‐metals were found Among the CoX′MnAl compounds with structure T II , we find that in cases of four out of five compounds, there is indeed a gap in the spin down band. However, the gap does not extend through the Fermi level for any of the compounds.…”

Section: Resultscontrasting

confidence: 83%

“…Recently few new quaternary half‐metallic ferromagnets with large Curie temperatures were reported where one out of the three magnetic components was a 4 d element. This work on CoX′Y′Si series (X′ covers all nine elements in the row of 4 d transition metals and Y′ = Fe,Mn) made an attempt to go beyond only reporting new half‐metals, by performing an in‐depth study on the relative importances of 3 d and 4 d elements affecting half‐metallic behavior.…”

Section: Introductionmentioning

confidence: 99%

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Half‐Metallicity in Quaternary Heusler Alloys with 3d and 4d Elements: Observations and Insights from DFT Calculations

Ghosh

2019

Physica Status Solidi (b)

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In this work, important insights into the evolution of half‐metallicity in quaternary Heusler alloys are provided. Employing ab initio electronic structure methods we study 18 quaternary Heusler compounds having the chemical formula CoX′Y′Al, where Y′ = Mn, Fe; and X′ a 4d element. Along with the search for new materials for spintronics applications, the trends in structural, electronic, magnetic properties, and Curie temperature are investigated. Comparative studies with the compounds in the quaternary series CoX′Y′Si with X′ materials from the 3d and 4d transition metal series in the periodic table have been made. We observe that the half‐metallic behavior depends primarily on the crystal structure type based on atomic arrangements and the number of valence electrons. As long as these two are identical, the electronic structures and the magnetic exchange interactions bear close resemblances. Consequently, the materials exhibit identical electronic properties, by and large. The roles of different transition metal atoms in affecting the hybridizations and their correlations with the above observations are analyzed. This work, therefore, provides important perspectives regarding the underlying physics of half‐metallic behavior in quaternary Heusler compounds which goes beyond specifics of a given material. This, thus, paves the way for smart prediction of new half‐metals. This work also figures out an open problem of understanding how different ternary Heuslers with different electronic behavior may lead to half‐metallic behavior in quaternary Heuslers with 4d transition metal elements.

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“…The compound CoMnYAl has total moment 4

μ_{B} / f . u .

with N V = 22, thus follows M =

| N_{normalV} - 18 |

Section: Resultssupporting

confidence: 87%

Section: Resultscontrasting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Half‐Metallicity in Quaternary Heusler Alloys with 3d and 4d Elements: Observations and Insights from DFT Calculations

Ghosh

2019

Physica Status Solidi (b)

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“…23,29,30 The Wyckoff positions of constituents are decided by fixing the As at 4a (0, 0, 0) position, while permuting the positions of remaining atoms. The QHAs generally crystallze in cubic structure with F-43m space group.…”

Section: Structural Propertiesmentioning

confidence: 99%

Exploration of highly correlated Co‐based quaternary Heusler alloys for spintronics and thermoelectric applications

Seh

Gupta

2019

Int J Energy Res

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Summary The half‐metallic character of new quaternary Heusler alloys CoXMnAs (X = Ru, Rh) is established along with their thermoelectric, mechanical, and thermodynamic properties. The optimization of energy suggests that alloys are stable in Y2‐type structure with a ferromagnetic character. The electronic band profile through generalized gradient approximation and modified Becke‐Johnson potential indicates the metallic character of alloys. However, with inclusion of Hubbard potential to generalized gradient approximation, the alloys depict half‐metallic character with semiconducting nature in spin‐down state. The alloys possess high magnetic moment, CoRuMnAs has 5 μB, whereas CoRhMnAs has 6 μB, following Slater‐Pauling rule MT = ZT − 24. The narrow band gap in spin‐down channel enhances the thermoelectric properties. The maximum value for thermopower (|S|) obtained is 44.3 and 53.44 μV/K for CoRuMnAs and CoRhMnAs, respectively. The variation of electrical conductivity, Seebeck coefficient, and figure of merit affirm increasing trend with temperature, which is a good indication of materials to be used in thermoelectric technology. The mechanical stability along with ductile nature of alloys is determined through elastic constants. Further, we have calculated thermodynamic properties and have established their dependence on temperature and pressure using quasi‐harmonic Debye model. The half‐metallic nature with efficient thermoelectric parameters strongly supports the possible application of alloys for spin devices and green energy generation.

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“…The half-metallic (HM) character in them also triggers their applicability in magneto-electronic devices. 8,9 HAs are grouped in four types: the ternary semi-Heusler alloys (C1 b ) XYZ, 10,11 the full-Heuslers with L2 1 structure and X 2 YZ composition, 12 inverse HAs (XA) X 2 YZ, 13 and the quaternary Heusler materials XX ˈYZ 14,15 ; X and Y represent d-block metals and Z a pgroup element. 6,7 Similarly, they also possess tunable electronic structure and high Curie temperatures.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure, mechanical, thermoelectric, optical, and thermodynamic properties of yttrium‐based quaternary Heusler alloys

Singh

Gupta

2019

Int J Energy Res

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Summary We give a detailed study of ground state properties, magnetism, mechanical, thermoelectric, thermodynamic, and optical properties of rare‐earth–based quaternary Heusler YFeMnAl and YFeMnGa alloys using the DFT and post‐DFT methods. The structure optimizations, display the LiMgPdSn‐type structure as stable phase with F‐43 m symmetry. The spin‐polarized band structure shows the alloys as perfect half‐metallics with indirect band gap of 0.364 eV in YFeMnAl and 0.391 eV in YFeMnGa. The magnetism also supports their half‐metallic character with an integral value of 3.00 μB estimated using the Slater‐Pauling curve rule. Mechanical stability is calculated using the elastic constants which define their ductile nature. Transport coefficients are investigated to see their capability as green energy sources where thermopower “S” measurements at room temperature are −29 μVK−1 for YFeMnAl and −9 μVK−1 for YFeMnGa, with negative sign displaying their n‐type majority heat carriers. Conversion efficiency of these materials descripts the figure of merit as 0.22 for YFeMnAl and 0.86 for YFeMnGa, respectively. The thermodynamic parameters like the heat capacity, Debye temperature, Grüneisen parameter, thermal expansion coefficient, and volume against pressure and temperature are sued to infer their stability at extreme conditions.

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New quaternary half-metallic ferromagnets with large Curie temperatures

Cited by 135 publications

References 49 publications

Half‐Metallicity in Quaternary Heusler Alloys with 3d and 4d Elements: Observations and Insights from DFT Calculations

Half‐Metallicity in Quaternary Heusler Alloys with 3d and 4d Elements: Observations and Insights from DFT Calculations

Exploration of highly correlated Co‐based quaternary Heusler alloys for spintronics and thermoelectric applications

Electronic structure, mechanical, thermoelectric, optical, and thermodynamic properties of yttrium‐based quaternary Heusler alloys

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