Electronic structure of doped Sr2VO4

Singh, David J.; Papaconstantopoulos, D. A.; Krakauer, Henry; Klein, B. M.; Pickett, Warren E.

doi:10.1016/0921-4534(91)90605-x

Cited by 11 publications

(12 citation statements)

References 16 publications

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“…A sharp peak around the Fermi level appears in the DOS, which indicates that the ground state is a paramagnetic metal. A similar result has been obtained by Singh et al 22) These results show that the LDA result contradicts the experimental results for Sr 2 VO 4 . On the other hand, as we will see later, the Hartree-Fock approximation for the effective Hamiltonian, also underlying the commonly used LDA þ U approach, 27) indicates that the ground state is a complete ferromagnetic insulator.…”

Section: Conventional Approachsupporting

confidence: 86%

Ground-State Properties and Optical Conductivity of the Transition Metal Oxide Sr₂VO₄

Imai

Imada

2006

J. Phys. Soc. Jpn.

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Combining first-principles calculations with a technique for many-body problems, we investigate the properties of the transition metal oxide Sr 2 VO 4 from the microscopic point of view. By using the local density approximation (LDA), the high-energy band structure is obtained, while screened Coulomb interactions are derived from the constrained LDA and the GW method. The renormalization of the kinetic energy is determined from the GW method. By these downfolding procedures, an effective Hamiltonian at low energies is derived. Applying the path integral renormalization group method to this Hamiltonian, we obtain ground-state properties such as the magnetic and orbital orders. Obtained results are consistent with available experimental data. We find that Sr 2 VO 4 is close to the metal-insulator transition. Furthermore, because of the coexistence and competition of ferromagnetic and antiferromgnetic exchange interactions in this system, an antiferromagnetic and orbital-ordered state with a nontrivial and large unit cell structure is predicted in the ground state. The calculated optical conductivity shows characteristic shoulder structure in agreement with the experimental results. This suggests an orbital selective reduction of the Mott gap.

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Section: Conventional Approachsupporting

confidence: 86%

Ground-State Properties and Optical Conductivity of the Transition Metal Oxide Sr₂VO₄

Imai

Imada

2006

J. Phys. Soc. Jpn.

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“…(ii) the electronic excitation spectrum of the V 4+ ions that supports a scenario of a novel ordered state in terms of an alternating spin-orbital order in Sr 2 VO 4 .…”

Section: Discussionmentioning

confidence: 99%

“…3,9,17 A further broad anomaly, also visible at 35 K in the magnetic susceptibility, was reported earlier. 7 Since this feature varies rather strongly from one sample to another, it may not be an intrinsic property of tetragonal Sr 2 VO 4 . The peaks present in the magnetic susceptibility around 35 K could be attributed to Sr 3 V 2 O 7 as a secondary phase.…”

Section: Sample Preparation and Experimental Detailsmentioning

confidence: 99%

“…Based on these similarities, several theoretical groups have suggested that doped Sr 2 VO 4 could be superconducting. [3][4][5] The excruciating difficulty of synthesizing a polycrystalline powder of the pristine material gives less flexibility than in the cuprates to play with the stochiometry. While superconductivity has been elusive, Sr 2 VO 4 passes as a function of temperature through a number of different electronic phases, which are not fully understood and which have not been observed in the cuprate family.…”

Section: Introductionmentioning

confidence: 99%

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Optical study of phonons and electronic excitations in tetragonal Sr2VO4

et al. 2011

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We report on the optical excitation spectra in Sr 2 VO 4 . The phonon modes are assigned and their evolution with temperature is discussed in the frame of the different phase transitions crossed upon cooling. Besides the expected infrared-active phonons, we observe two additional excitations at about 290 and 840 cm −1 , which could correspond to electronic transitions of the V 4+ ions. Our experimental results are discussed in the context of recent experimental and theoretical studies of this material with a unique spin-orbital ground state.

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“…7 Consequently, it was suggested that Sr 2 VO 4 could become superconducting upon applying chemical pressure by doping or external pressure. 8,9 While the system could not be driven toward superconductivity, it turned out to be a model system for studying the interplay of orbital-lattice, spin-orbital, and superexchange interactions. [10][11][12][13] In tetragonal Sr 2 VO 4 with space group I 4 /mmm, 14,15 the octahedrally coordinated V 4+ ions occupy a square lattice in the ab plane (see Fig.…”

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confidence: 99%

Alternating spin-orbital order in tetragonal Sr2VO4

et al. 2011

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Considering spin-orbit coupling, the tetragonal crystal field, and all relevant superexchange processes including quantum interference, we derive expressions for the energy levels of the vanadium ions in tetragonal Sr 2 VO 4 . The used parameters of the model Hamiltonian allow us to describe well the excitation spectra observed in neutron scattering and optical experiments at low temperatures. The free energy exhibits a minimum which corresponds to a novel alternating spin-orbital order with strong thermal fluctuation of the orbital mixing parameter. In many transition-metal compounds the orbital degrees of freedom play a decisive role in determining the groundstate properties of materials such as manganites, titanates, or vanadates. 1 When contributions of the orbital moment and spin-orbit coupling are not negligible, a separation between spin and orbital degrees of freedom is not adequate anymore and the system is better described by an effective total angular momentum. 2,3 If spin-orbit coupling competes with electron-phonon or exchange interactions even strong fluctuation regimes can arise. [4][5][6] The system investigated here is the layered insulator Sr 2 VO 4 with tetragonal symmetry, which early on has come into focus as an isostructural d 1 analog of La 2 CuO 4 . 7 Consequently, it was suggested that Sr 2 VO 4 could become superconducting upon applying chemical pressure by doping or external pressure. 8,9 While the system could not be driven toward superconductivity, it turned out to be a model system for studying the interplay of orbital-lattice, spin-orbital, and superexchange interactions. [10][11][12][13] In tetragonal Sr 2 VO 4 with space group I 4 /mmm, 14,15 the octahedrally coordinated V 4+ ions occupy a square lattice in the ab plane (see Fig. 1). The magnetic ground state has been claimed to be antiferromagnetic with transition temperatures in the range 10-100 K determined from susceptibility measurements, but long-range order has remained evasive on the basis of neutron-diffraction studies. 14,16,17 Recent studies have established the occurrence of a magnetostructural phase transition extending over a temperature range from 94 K to 122 K. Both the high-temperature and the low-temperature structure are tetragonal and reportedly coexist within this range. 11 Specific heat data have revealed two distinct broad maxima occurring at 98 K and 127 K mirroring the borders of the two-phase regime. 18,19 The disappearance of the high-temperature phase is accompanied by a significant drop in the susceptibility at about 100 K, which has been attributed to the onset of long-range antiferromagnetic (AFM) and orbital order. 11 Theoretically, the ground state of Sr 2 VO 4 has been interpreted in terms of stripelike orbital and collinear AFM spin order 10 or an ordering of magnetic octupoles. 12 Inelastic neutron scattering has revealed two excitations at about 120 meV, which have been assigned to the highest lying doublet of the V 4+ t 2g levels. 13 Recent optical experiments have reported excitations at 31 ...

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Electronic structure of doped Sr2VO4

Cited by 11 publications

References 16 publications

Ground-State Properties and Optical Conductivity of the Transition Metal Oxide Sr₂VO₄

Ground-State Properties and Optical Conductivity of the Transition Metal Oxide Sr₂VO₄

Optical study of phonons and electronic excitations in tetragonal Sr2VO4

Alternating spin-orbital order in tetragonal Sr2VO4

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Electronic structure of doped Sr2VO4

Cited by 11 publications

References 16 publications

Ground-State Properties and Optical Conductivity of the Transition Metal Oxide Sr2VO4

Ground-State Properties and Optical Conductivity of the Transition Metal Oxide Sr2VO4

Optical study of phonons and electronic excitations in tetragonal Sr2VO4

Alternating spin-orbital order in tetragonal Sr2VO4

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Ground-State Properties and Optical Conductivity of the Transition Metal Oxide Sr₂VO₄

Ground-State Properties and Optical Conductivity of the Transition Metal Oxide Sr₂VO₄