Large spin gaps in the half-metals 
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 (
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=Mn, Fe, Co) with 
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 dimers

Deng, Jun; Liu, Ning; Guo, Jiangang; Chen, Xiaolong

doi:10.1103/physrevb.99.184409

Cited by 14 publications

(16 citation statements)

References 65 publications

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“…33 Besides, N 2 dimers were predicted to form other nitrides with main group element and 3d metals, which can be a metal with excellent thermal and electrical conductivity for SiN 4 36 and a half-metal for FeN 4 . 37 More novel magnetic and other emergent properties are expected in these compounds containing O 2 and N 2 dimers. 38 Hayyan and co-workers recently gave a very comprehensive review on the generation and implications of O 2 − .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…We note that N 2 dimers can also induce magnetism in some nitrides if there exist unpaired electrons in its π*orbitals, such as SrN . Besides, N 2 dimers were predicted to form other nitrides with main group element and 3 d metals, which can be a metal with excellent thermal and electrical conductivity for SiN 4 and a half-metal for FeN 4 . More novel magnetic and other emergent properties are expected in these compounds containing O 2 and N 2 dimers .…”

Section: Resultsmentioning

confidence: 99%

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Molecular Oxygen-Induced Ferromagnetism and Half-Metallicity in α-BaNaO₄: A First-Principles Study

2020

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Molecule oxygen resembles 3d and 4f metals in exhibiting long-range spin ordering and electron strong correlated behaviors in compounds. The ferromagnetic spin ordering and half-metallicity, however, are quite elusive and have not been well acknowledged. In this article, we address this issue to study how spins will interact each other if the oxygen dimers are arranged in a different way from that in the known super-and per-oxides by first principles calculations. Based on the results of structure search, thermodynamic study and lattice dynamics, we show that tetragonal α-BaNaO4 is a stable halfmetal with a Curie temperature at 120 K, a first example in this class of compounds. Like 3d and 4f metals, the O2 dimer carries a local magnetic moment 0.5 μB due to the unpaired electrons in its π* orbitals. This compound can be regarded as forming from the O2 dimer layers stacking in a head to head way. Different from that in AO2 (A=K, Rb, Cs), the spins are both ferromagnetically coupled within and between the layers. Spin polarization occurs in π* orbitals with spin-up electrons fully occupying the valence band and spin-down electrons partially the conduction band, forming the semiconducting and metallic channels, respectively. Our results highlight the importance of geometric arrangement of O2 dimers in inducing ferromagnetism and other novel properties in O2 dimer containing compounds. ASSOCIATED CONTENT Supporting Information. Lattice parameters; elastic constants; details of estimation coupling constant; phonon spectra and band structures of BaNaOx; molecular dynamics simulations of BaNaO4; more band structure results of BaNaO4; shifted configuration of RbO2; structures and formation enthalpies of related compounds.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Molecular Oxygen-Induced Ferromagnetism and Half-Metallicity in α-BaNaO₄: A First-Principles Study

2020

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“…By contrast, the calculated results show that hP6-WN 2 is in a semiconducting state at equilibrium but is driven into metallic states by the Vickers indentation loadings near the peak stress. The electronic densities of states of the six tungsten nitrides at equilibrium and under Vickers indentation shear loadings at the indicated strains near the peak stress values along (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)[001] and (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)[110] shear directions corresponding to the stress-strain relations discussed above are shown in Figs. S2-S7 [39].…”

Section: F Hexagonal Hp22-w 5 Nmentioning

confidence: 99%

“…Transition-metal nitrides have attracted much attention in recent years due to their rich characteristics as hightemperature ceramics, superconductors, magnets, and catalysts, etc. [1][2][3][4][5][6][7][8][9]. Among these materials, tungsten nitrides represent a distinct family of compounds that exhibit high melting temperatures and desirable mechanical properties [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Indentation-strain stiffening in tungsten nitrides: Mechanisms and implications

Chen

2020

Phys. Rev. Materials

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We report on a systematic computational study of ideal strengths, i.e., the lowest stresses needed to destabilize a perfect crystal under a variety of loading conditions for six stable and metastable tungsten nitrides identified by advanced crystal structure search algorithms. We employ first-principles calculations to determine stress-strain relations and examine the corresponding atomistic bonding changes for a microscopic understanding of the structural deformation modes. The obtained results show that, in stark contrast to many previously studied transition-metal borides, carbides, and also most nitrides, the tungsten nitrides exhibit surprisingly broad and common patterns of strain-stiffening effects under indentation strains. These extraordinary behaviors are attributed to the favorable bonding arrangements in these materials, including the strong and well-connected W-W metallic bonds and N ≡ N bonds in combination with W-N covalent bonds, which together create a strong three-dimensional bonding network that is capable of resisting large-indentation shear deformations, thereby greatly enhancing the corresponding mechanical strength that is directly responsible for the superior experimentally measured hardness results. These findings provide insights for elucidating unusual indentation strength enhancements in these materials and offer guidelines for exploring experimental synthesis and optimization of the presently identified and potentially additional very hard to superhard materials. These insights are also crucial for understanding the fundamental relationship between crystal and chemical bonding structures and the associated mechanical properties under a wide range of loading conditions in diverse application environments.

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“…The diagrams of phonon frequencies at high symmetry points in the Brillouin zone of Ca 0.75 Cr 0.25 O, Ca 0.5 Cr 0.5 O, and Ca 0.25 Cr 0.75 O are shown by Figures 1 – 3 , respectively. These figures depicted that all branches of phonons have positive frequencies, and there are no negative frequencies (Deng et al, 2019 ), confirming the dynamic stability of Ca 0.75 Cr 0.25 O, Ca 0.5 Cr 0.5 O, and Ca 0.25 Cr 0.75 O compounds.…”

Section: Resultsmentioning

confidence: 66%

Recent Insights Into Electronic Performance, Magnetism and Exchange Splittings in the Cr-substituted CaO

Doumi¹,

Mokaddem²,

Tadjer³

et al. 2020

Front. Chem.

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The first-principles computations of density functional theory are employed to characterize the structural properties, electronic structures, and ferromagnetism induced by Cr impurities in Ca 1-x Cr x O compounds at concentrations x = 0. 25, 0.5, and 0.75. The dynamic stability is performed by the phonon spectra calculations. The structural parameters are computed by using Wu-Cohen generalized gradient approximation, while the electronic and magnetic properties are determined by the accurate Tran-Blaha-modified Becke-Johnson exchange potential. The crystal field, direct and indirect exchange splittings were investigated to determine the origin and stability of ferromagnetic state configuration. The Ca 1-x Cr x O systems have right half-metallicities, which are verified by the spin polarization of 100% and the integer values of total magnetic moments. The Ca 0.75 Cr 0.25 O, Ca 0.5 Cr 0.5 O, and Ca 0.25 Cr 0.75 O are half-metallic ferromagnetic with flip-gaps of 1.495, 0.888, and 0.218 eV, respectively. Therefore, the Ca 1-x Cr x O materials are suitable candidates for possible applications of spin-injection in future semiconductors spintronics.

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Large spin gaps in the half-metals MN4 ( M =Mn, Fe, Co) with N2 dimers

Cited by 14 publications

References 65 publications

Molecular Oxygen-Induced Ferromagnetism and Half-Metallicity in α-BaNaO₄: A First-Principles Study

Molecular Oxygen-Induced Ferromagnetism and Half-Metallicity in α-BaNaO₄: A First-Principles Study

Indentation-strain stiffening in tungsten nitrides: Mechanisms and implications

Recent Insights Into Electronic Performance, Magnetism and Exchange Splittings in the Cr-substituted CaO

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Large spin gaps in the half-metals MN4 ( M =Mn, Fe, Co) with N2 dimers

Cited by 14 publications

References 65 publications

Molecular Oxygen-Induced Ferromagnetism and Half-Metallicity in α-BaNaO4: A First-Principles Study

Molecular Oxygen-Induced Ferromagnetism and Half-Metallicity in α-BaNaO4: A First-Principles Study

Indentation-strain stiffening in tungsten nitrides: Mechanisms and implications

Recent Insights Into Electronic Performance, Magnetism and Exchange Splittings in the Cr-substituted CaO

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Product

Resources

About

Molecular Oxygen-Induced Ferromagnetism and Half-Metallicity in α-BaNaO₄: A First-Principles Study

Molecular Oxygen-Induced Ferromagnetism and Half-Metallicity in α-BaNaO₄: A First-Principles Study