Hole bipolaron formation at (100) MgO/CaO epitaxial interface

Bondarenko, N. G.; Eriksson, Olle; Skorodumova, Natalia V.

doi:10.1103/physrevb.89.125118

Cited by 10 publications

(12 citation statements)

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“…The barriers for polaron transitions were calculated using both the linear interpolation scheme (LIS) as in our previous work [66] and the nudged elastic band method (N EB) [67]. N EB is an efficient method for studying atomic and molecular diffusion, phase transitions, chemical reactions as well as polaronic transitions in oxides [67][68][69][70][71].…”

Section: II Details Of Calculationsmentioning

confidence: 99%

“…To properly model small polarons one needs a method adequately describing the on-site charge localization and lattice distortions around this site [66,[72][73][74][75]. Electron localization in correlated d− and f −metal oxides usually cannot be correctly described by standard DF T approximations, which due to the presence of the self-interaction term tend to overestimate the stability of the delocalized solution.…”

Section: A a Electron Localization In Oxygen Deficient γ − W O3mentioning

confidence: 99%

“…Another way to cure the self-interaction problem of standard DF T is to employ the so-called hybrid functionals, where a certain amount of nonlocal Fock exchange is added [80]. Both approaches have successfully been used to describe electron localization or small polaron formation in different oxides [53,66,[72][73][74][75]81]. Hybrid functionals are more computationally demanding than DF T +U and therefore their usage is limited to rather small unit cells.…”

Section: A a Electron Localization In Oxygen Deficient γ − W O3mentioning

confidence: 99%

“…First, within the DF T + U W approach we varied U W from 2 to 12 eV in the manner described in Ref. [66]. We analyzed the localization patterns for different values and found that for U ef f = 8eV and higher almost precisely one electron was localized at the d-orbitals of each of the two W 5+ tungsten atoms.…”

Section: A a Electron Localization In Oxygen Deficient γ − W O3mentioning

confidence: 99%

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Polaron mobility in oxygen-deficient and lithium-doped tungsten trioxide

2015

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Electron localization and polaron mobility in oxygen-deficient as well as Li-doped monoclinic tungsten trioxide have been studied in the adiabatic limit in the framework of density functional theory. We show that small polarons formed in the presence of oxygen vacancy prefer the bipolaronic W 5+ -W 5+ configuration, whereas the W 6+ -W 4+ configuration is found to be metastable. Our calculations suggest that bipolarons are tightly bound by the vacancy and therefore largely immobile. On the contrary, polarons formed as a result of Li intercalation can be mobile; the activation energy for polaron jumping in this case varies between 98 and 124 meV depending on the crystallographic direction.

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Section: II Details Of Calculationsmentioning

confidence: 99%

Section: A a Electron Localization In Oxygen Deficient γ − W O3mentioning

confidence: 99%

Section: A a Electron Localization In Oxygen Deficient γ − W O3mentioning

confidence: 99%

Section: A a Electron Localization In Oxygen Deficient γ − W O3mentioning

confidence: 99%

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Polaron mobility in oxygen-deficient and lithium-doped tungsten trioxide

2015

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“…Such 7-site SPs can be joined together in different configurations forming larger FM droplets, for example, involving 12-, 17-or 21-sites [6,7]. Unlike classical polarons, where an electron is trapped due to a strong electron-lattice interaction [8,9], spin polarons are thought to localize largely due to magnetic interaction [10,11]. However, cooperative spin-chargelattice effects are also important for SPs as the formation of the M n 3+ (e 1 g ) state leads to the symmetry breaking by Jan-Teller distortions becoming more pronounced as the number of M n 3+ atom increases.…”

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confidence: 99%

Spin-polaron formation and magnetic state diagram in La-doped CaMnO3

et al. 2017

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LaxCa1−xM nO3 (LCMO) has been studied in the framework of density functional theory (DFT) using Hubbard-U correction. We show that the formation of spin-polarons of different configurations is possible in the G-type antiferromagentic phase. We also show that the spin-polaron (SP) solutions are stabilized due to an interplay of magnetic and lattice effects at lower La concentrations and mostly due to the lattice contribution at larger concentrations. Our results indicate that the development of SPs is unfavorable in the C-and A-type antiferromagnetic phases. The theoretically obtained magnetic state diagram is in good agreement with previously reported experimental results.Perovskite CaM nO 3 -LaM nO 3 (CMO-LMO) system exhibits an outstandingly rich magnetic and structural polymorphism [1]. CaM nO 3 (CMO) is an orthorhombic (Pnma) semiconductor with the band gap of 3.07 eV [2]. Its magnetic ground state is the G-type antiferromagnetic (G-AFM) structure, where each spin-up (down) atom is surrounded by 6 spin-down (up) atoms. Such a magnetic ordering is thought to be governed by the super-exchange interaction along the M n. When trivalent La 3+ substitute atoms in the Ca 2+ sublattice extra valence electrons are added to the system. This extra charge can be redistributed among a large number of atoms or fully (or partially) localized at the d-orbitals of particular Mn atoms driving the double-exchange interaction in the mixed-valence. The Hund coupling may then assist the spin flip at the central site of the magnetic octahedron [5], thus forming a ferromagnetic (FM) 7-site droplet or the so-called 7-site spin-polaron (SP). Such 7-site SPs can be joined together in different configurations forming larger FM droplets, for example, involving 12-, 17-or 21-sites [6,7]. Unlike classical polarons, where an electron is trapped due to a strong electron-lattice interaction [8,9], spin polarons are thought to localize largely due to magnetic interaction [10,11]. However, cooperative spin-chargelattice effects are also important for SPs as the formation of the M n 3+ (e 1 g ) state leads to the symmetry breaking by Jan-Teller distortions becoming more pronounced as the number of M n 3+ atom increases. At a critical concentration the accumulated lattice deformation energy drives the magnetic transition to the C-type antiferromagnetic (C-AFM) state, which in La-doped CaM nO 3 is accompanied by the structural transition from Pnma orthorhombic to the P 1 /m monoclinic structure [1,6,[12][13][14][15].In Fig. 1 we summarize the available experimental data on the stability of the magnetic phases of La x Ca 1−x M nO 3 for x La < 0.2. The concentrations at which the magnetic transitions are reported to take place, vary depending on the experimental setups and applied methods, nonetheless, all the experiments clearly demonstrate the existence of four distinct regions (i-iv), described below.i. Concentration range 0 < x La < 0.01 − 0.03. For these small concentrations the G-AFM magnetic structure of CMO is preserved but the physical prop...

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