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-insulator heterointerfaces: Creation of half-metallicity and anionogenic ferromagnetism via double exchange

Zhang, Baomin; Cao, Chonglong; Li, Guowei; Liu, Feng; Ji, Wei-xiao; Zhang, Shufeng; Ren, Miaojuan; Zhang, Haikun; Qi, Fei; Zhong, Zhicheng; Yuan, Zhe; Yuan, Shengjun; Blake, Graeme R.

doi:10.1103/physrevb.97.165109

Cited by 2 publications

(7 citation statements)

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“…The a and b lattice parameters are essentially the same for the three samples, whereas the c lattice parameter significantly decreases as the salt ratio increases, leading to a decrease in cell volume. This implies a shrinkage of the BO 6 octahedra due to a shortening of the B-O bond lengths and could occur due to a varying proportion of [24], as discussed further below. Fig.…”

Section: Resultsmentioning

confidence: 99%

Ratio effect of salt fluxes on structure, dielectric and magnetic properties of La,Mn-doped PbBi2Nb2O9 Aurivillius phase

Wendari

Arief

Mufti

et al. 2020

Ceramics International

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The double-layer Aurivillius phase Pb 0.4 Bi 2.1 La 0.5 Nb 1.7 Mn 0.3 O 9 was synthesized by a molten salt method using a K 2 SO 4 /Na 2 SO 4 flux. The effect on the crystal structure, morphology, dielectric and magnetic properties of varying the molar ratio of the oxide precursors to salt flux was investigated. Single-phase products with an orthorhombic structure were obtained for oxide to salt ratios of between 1:5 and 1:9, whereas for lower concentrations of salt a pyrochlore impurity phase is found in the products. SEM showed anisotropic plate-like grains, the size of which increases for larger salt ratios. An investigation of the magnetic properties showed the presence of mixed Mn 3+ and Mn 4+ ; the unit cell volume of the single-phase products decreases as the proportion of salt increases, which implies a higher proportion of smaller Mn 4+ cations. This can be explained by the oxide ion donating properties (oxobasicity) of the molten salt mixture, which produces an oxidizing environment during synthesis. The best dielectric properties are obtained for an oxide to salt ratio of 1:7, exhibiting relaxor ferroelectric behavior. This is also the ratio at which the most pronounced ferromagnetic properties are observed, resulting from double-exchange interactions between Mn 3+ and Mn 4+ , the proportions of which are approximately equal. Pb 0.4 Bi 2.1 La 0.5 Nb 1.7 Mn 0.3 O 9 synthesized under these conditions thus exhibits optimal multiferroic properties.

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Section: Resultsmentioning

confidence: 99%

Ratio effect of salt fluxes on structure, dielectric and magnetic properties of La,Mn-doped PbBi2Nb2O9 Aurivillius phase

Wendari

Arief

Mufti

et al. 2020

Ceramics International

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“…Similar to La1-xAxMnO3 (A=Ca, Sr, Ba), where the electron hopping from Mn 3+ to Mn 4+ through double exchange, 34 the itinerant electrons in the π* orbitals could hop from O2 2-to O2 -in the (001) plane mediated by Na + ions, guaranteeing the spins parallel. 20 Along the [001] direction, a positive J2 could be explained as FM interaction through direct exchange interactions among the head-to-head O2 dimers. All neighboring O2-dimer layers are coupled ferromagnetically as expected.…”

Section:  Results and Discussionmentioning

confidence: 99%

“…Its chemical formula can be written as to O 2 − in the (001) plane mediated by Na + ions, guaranteeing the spins are parallel. 20 Along the [001] direction, a positive J 2 could be explained as FM interaction through direct exchange interactions among the head-to-head O 2 dimers. All neighboring O 2 -dimer layers are coupled ferromagnetically as expected.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…19 It is argued to emerge anionogenic ferromagnetism and half-metallicity in the interface of KO2/BaO2 through double exchange interactions of O2 2-and O2 -from the first principles calculations. 20 A question arises, is a long-range FM ordering possible in a bulky molecule oxygen containing compound as in a 3d metal counterpart? If so, can a half metal be evolved from the FM?…”

Section:  Introductionmentioning

confidence: 99%

“…19 It is argued from first-principles calculations that anionogenic ferromagnetism and halfmetallicity will emerge at the interface of KO 2 /BaO 2 through double-exchange interactions of O 2 2− and O 2 − . 20 A question arises: Is long-range FM ordering possible in a bulky molecular oxygen-containing compound, as it is in a 3d metal counterpart? If so, can a half-metal be evolved from the 10 In contrast, the ground state of RbO 2 is experimentally confirmed to be AFM, 5 for all the O 2 dimers align parallel.…”

Section: ■ Introductionmentioning

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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2p -insulator heterointerfaces: Creation of half-metallicity and anionogenic ferromagnetism via double exchange

Cited by 2 publications

References 50 publications

Ratio effect of salt fluxes on structure, dielectric and magnetic properties of La,Mn-doped PbBi2Nb2O9 Aurivillius phase

Ratio effect of salt fluxes on structure, dielectric and magnetic properties of La,Mn-doped PbBi2Nb2O9 Aurivillius phase

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

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2p -insulator heterointerfaces: Creation of half-metallicity and anionogenic ferromagnetism via double exchange

Cited by 2 publications

References 50 publications

Ratio effect of salt fluxes on structure, dielectric and magnetic properties of La,Mn-doped PbBi2Nb2O9 Aurivillius phase

Ratio effect of salt fluxes on structure, dielectric and magnetic properties of La,Mn-doped PbBi2Nb2O9 Aurivillius phase

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

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