Alexander Poteryaev - Academia.edu (original) (raw)

Papers by Alexander Poteryaev

Research paper thumbnail of Hydrogenation-driven formation of local magnetic moments in FeO2Hx

Physical Review B

The electronic and magnetic properties of recently discovered new important constituent of the Ea... more The electronic and magnetic properties of recently discovered new important constituent of the Earth's lower mantle FeO2H were investigated by means of the density functional theory combined with the dynamical mean field theory (DFT+DMFT). Addition of the hydrogen to the parent FeO2 compound, which is an uncorrelated bad metal, destroys the most important ingredient of its electronic structure-O-O molecular orbitals. In effect physical properties of FeO2 and FeO2H turn to be completely different, FeO2H is a correlated metal with a mass renormalization, m * /m ∼ 1.7, and magnetic moments on Fe ions become localized with the Curie-Weiss type of uniform magnetic susceptibility.

Research paper thumbnail of Influence of Molecular Orbitals on Magnetic Properties of FeO2Hx

Molecules

Recent discoveries of various novel iron oxides and hydrides, which become stable at very high pr... more Recent discoveries of various novel iron oxides and hydrides, which become stable at very high pressure and temperature, are extremely important for geoscience. In this paper, we report the results of an investigation on the electronic structure and magnetic properties of the hydride FeO 2 H x , using density functional theory plus dynamical mean-field theory (DFT+DMFT) calculations. An increase in the hydrogen concentration resulted in the destruction of dimeric oxygen pairs and, hence, a specific band structure of FeO 2 with strongly hybridized Fe- t 2 g -O- p z anti-bonding molecular orbitals, which led to a metallic state with the Fe ions at nearly 3+. Increasing the H concentration resulted in effective mass enhancement growth which indicated an increase in the magnetic moment localization. The calculated static momentum-resolved spin susceptibility demonstrated that an incommensurate antiferromagnetic (AFM) order was expected for FeO 2 , whereas strong ferromagnetic (FM) fluct...

Research paper thumbnail of XPS evidence of degradation mechanism in СH3NH3PbI3 hybrid perovskite

Journal of Physics: Condensed Matter

The paper presents the results of measurements of XPS valence band spectra of SiO 2 /MAPbI 3 hybr... more The paper presents the results of measurements of XPS valence band spectra of SiO 2 /MAPbI 3 hybrid perovskites subjected to irradiation with visible light and annealing at an exposure of 0-1000 hours. It is found from XPS survey spectra that in both cases (irradiation and annealing) a decrease in the I:Pb ratio is observed with aging time, which unambiguously indicates PbI 2 phase separation as a photo and thermal product of degradation. The comparison of the XPS valence band spectra of irradiated and annealed perovskites with density functional theory calculations of the MAPbI 3 and PbI 2 compounds have showed a systematic decrease in the contribution of I 5p-states and allowed us to determine the threshold for degradation, which is 500 hours for light irradiation and 200 hours for annealing.

Research paper thumbnail of Electronic correlations and competing orders in multiorbital dimers: A cluster DMFT study

Physical Review B

We investigate the violation of the first Hund's rule in 4d and 5d transition metal oxides that f... more We investigate the violation of the first Hund's rule in 4d and 5d transition metal oxides that form solids of dimers. Bonding states within these dimers reduce the magnetization of such materials. We parametrize the dimer formation with realistic hopping parameters and find not only regimes, where the system behaves as a Fermi liquid or as a Peierls insulator, but also strongly correlated regions due to Hund's coupling and its competition with the dimer formation. The electronic structure is investigated using the cluster dynamical mean-field theory for a dimer in the two-plane Bethe lattice with two orbitals per site and 3/8-filling, that is three electrons per dimer. It reveals dimerantiferromagnetic order of a high-spin (double exchange) state and a low-spin (molecular orbital) state. At the crossover region we observe the suppression of long-range magnetic order, fluctuation enhancement and renormalization of electron masses. At certain interaction strengths the system becomes an incoherent antiferromagnetic metal with well defined local moments.

Research paper thumbnail of Unexpected 3+ valence of iron in FeO2, a geologically important material lying "in between" oxides and peroxides

Scientific reports, Jan 11, 2017

Recent discovery of the pyrite FeO2, which can be an important ingredient of the Earth's lowe... more Recent discovery of the pyrite FeO2, which can be an important ingredient of the Earth's lower mantle and which in particular may serve as an extra source of water in the Earth's interior, opens new perspectives for geophysics and geochemistry, but this is also an extremely interesting material from physical point of view. We found that in contrast to naive expectations Fe is nearly 3+ in this material, which strongly affects its magnetic properties and makes it qualitatively different from well known sulfide analogue - FeS2. Doping, which is most likely to occur in the Earth's mantle, makes FeO2 much more magnetic. In addition we show that unique electronic structure places FeO2 "in between" the usual dioxides and peroxides making this system interesting both for physics and solid state chemistry.

Research paper thumbnail of Magnetic properties ofFe1−xNixalloy from CPA+DMFT perspectives

Physical Review B, 2016

We use a combination of the coherent potential approximation and dynamical mean field theory to s... more We use a combination of the coherent potential approximation and dynamical mean field theory to study magnetic properties of the Fe1−xNix alloy from a first principles. Calculated uniform magnetic susceptibilities have a Curie-Weiss-like behavior and extracted effective temperatures are in agreement with the experimental results. The individual squared magnetic moments obtained as function of nickel concentration follow the same trends as experimental data. An analysis of the ionic and spin weights shows a possibility of a high-spin to intermediate-and low-spin states transitions at high temperatures.

Research paper thumbnail of Momentum-resolved spectroscopy of correlated metals: A view from dynamical mean field theory

Data Revues 16310705 V10i6 S1631070509001042, Jul 1, 2009

... E-mail addresses: jan.tomczak@polytechnique.edu (JM Tomczak), alexander.poteryaev@ polytechni... more ... E-mail addresses: jan.tomczak@polytechnique.edu (JM Tomczak), alexander.poteryaev@ polytechnique.edu (AI Poteryaev), biermann@cpht.polytechnique.fr (S. Biermann). ... Phys. 3 (2007) 168. [15] IA Nekrasov, K. Held, G. Keller, DE Kondakov, Th. ...

Research paper thumbnail of Electronic structure of CuV_2S_4

The delafossite type CuFeO2 single crystal was studied by means of x-ray emission and x-ray photo... more The delafossite type CuFeO2 single crystal was studied by means of x-ray emission and x-ray photoelectron spectroscopy. The valence state of Cu ions was found to be 1+, whereas Fe-ions were found to be trivalent in the high-spin S=5/2 state. The x-ray emission (Cu L_alpha , Fe L_alpha and O K_alpha ) and photoelectron spectra were compared to the results

Research paper thumbnail of Electronic structure of advanced materials studied by x-ray emission spectroscopy

The 17th international conference on x-ray and inner-shell processes, 1997

ABSTRACT High resolution soft x-ray emission spectroscopy with high spatial resolution is used to... more ABSTRACT High resolution soft x-ray emission spectroscopy with high spatial resolution is used to study of the electronic structure and characterize advanced materials: high-Tc superconductors, transition metal compounds, porous silicon, solid-solid buried interfaces and hard materials. In high-Tc, the main attention is focused on the analysis of oxygen-cation interactions and the determination of the location of impurity atoms. In transition metal compounds the participation of different electronic states of constitute atoms in the valence band is analyzed and correctness of LDA band structure calculations is estimated. For CuFeO2 an unusual mutual position of the Cu3d and Fe3d bands was found which is attributed to strong electron-electron correlations. In porous silicon the local structure of silicon atoms is found to depend on the type of doping of the initial Si wafer. Solid-solid buried interfaces in thin semiconducting films irradiated by eximer laser are investigated. For the hard materials boron-carbonitride a structure consisting of hexagonal lattice planes of carbon and boron nitride is proposed. © 1997 American Institute of Physics.

Research paper thumbnail of Specific heat of a binary alloy within the CPA+DMFT method

Research paper thumbnail of Dynamical mean field approach for non-collinear doped antiferromagnets

We have generalized a dynamical mean field approach in the iterative perturbation scheme (H.Kajue... more We have generalized a dynamical mean field approach in the iterative perturbation scheme (H.Kajueter, G.Kotliar, Phys.Rev.Lett.77,131 (1996)) to study the electronic structure of non-collinear magnetic states. A local approximation for the exact self-energy in d=∞ is found to be a very convenient approximation for spin-spiral magnetic configurations for real 2d- and 3d-lattices. We investigate a doped 2d-antiferromagnet in the one-band Hubbard model and show that the antiferromagnetic (AFM) state is unstable towards the formation of a spin spiral configuration. The quasiparticle peak (in the density of states) agrees well with the quantum Monte Carlo calculations. As the non-doped AFM insulator is unstable in this approach, we argue that instead of the Iterative Perturbation Theory, a more realistic description for magnetic systems is obtained with a transverse and longitudinal spin fluctuation approach which includes the Hartree-Fock terms in the ''bath`` Green-function. In...

Research paper thumbnail of Magnetostriction and ferroelectric state in AgCrS2

Journal of physics. Condensed matter : an Institute of Physics journal, Jan 30, 2015

The band structure calculations in the GGA+U approximation show the presence of additional lattic... more The band structure calculations in the GGA+U approximation show the presence of additional lattice distortions in the magnetically ordered phase of AgCrS2. The magnetostriction leads to the formation of long and short Cr-Cr bonds in the case when the respective Cr ions have the same or opposite spin projections. These changes in the Cr lattice are accompanied by distortions of the CrS6 octahedra, which in turn lead to the development of spontaneous electric polarization.

Research paper thumbnail of Combining density-functional and dynamical-mean-field theory for La1-xSrxTiO3

Physical Review B, 2000

ABSTRACT The dynamical-mean-field theory combined with the noncrossing approximation is used to s... more ABSTRACT The dynamical-mean-field theory combined with the noncrossing approximation is used to set up a scheme to study the electronic structure of strongly correlated electron systems. The noninteracting band structure is obtained from a density-functional calculation within the local-density approximation. With this method the doped Mott insulator La1-xSrxTi O3 is studied. Starting from first-principle calculations for a cubic and an orthorhombic system we determine the one-particle spectrum. Both one-particle spectra show a lower Hubbard band (seen as d1-->d0 transitions in photoemission experiments) and a quasiparticle resonance near the Fermi energy and the upper Hubbard band (d1-->d2 transitions in an inverse photoemission experiment). The upper Hubbard band develops a multipeak structure, a consequence of the consideration of all local two-particle correlations, which leads to the full multiplet structure in the atomic limit. The calculation for the orthorhombic system shows qualitative good agreement when compared with experimental photoemission spectra.

Research paper thumbnail of Valence-band spectra and electronic structure of CuFeO2

Physical Review B, 1997

... Tong-Rong Zhao Institute for Solid State Physics, University of Tokyo, 7-22-1, Roppongi, Mina... more ... Tong-Rong Zhao Institute for Solid State Physics, University of Tokyo, 7-22-1, Roppongi, Minato-ku, Tokyo 106, Japan Received 3 December 1996 ... The feed rod was suspended from the upper holder by a platinum wire and the lower seed, made from a sintered rod, was fixed ...

Research paper thumbnail of Electronic structure of superconducting inorganic polymer (SN)(x)

Physica C, 1999

... EZ Kurmaev a , AI Poteryaev a , VI Anisimov a , I. Karla b , A. Moewes c , * , B. Schneider b... more ... EZ Kurmaev a , AI Poteryaev a , VI Anisimov a , I. Karla b , A. Moewes c , * , B. Schneider b , M. Neumann b , DL Ederer d and RN Lyubovskaya e. ... The position sensitive detector is moved along the Rowland circle to the region of interest for the emission measurements. ...

Research paper thumbnail of Fermi Surface of CaVO3 perovskite: LDA+DMFT study

We present ab initio LDA+DMFT calculations of CaVO3 perovskite near Mott transition. The calculat... more We present ab initio LDA+DMFT calculations of CaVO3 perovskite near Mott transition. The calculated electronic structure and Fermi surface are in good agreement with an experimental data. The DMFT results are compared to conventional LDA band structure and an experimental data. The difference between the Fermi surfaces obtained by LDA+DMFT, LDA methods and de Haas-van Alphen data are discussed.

Research paper thumbnail of Coherent Peaks and Minimal Probing Depth in Photoemission Spectroscopy of Mott-Hubbard Systems

Physical Review Letters, 2006

We have measured hard x-ray photoemission spectra of pure vanadium sesquioxide (V 2 O 3) across i... more We have measured hard x-ray photoemission spectra of pure vanadium sesquioxide (V 2 O 3) across its metal-insulator transition. We show that, in the metallic phase, a clear correlation exists between the shakedown satellites observed in the vanadium 2p and 3p core-level spectra and the coherent peak measured at the Fermi level. Comparing experimental results and dynamical mean-field theory calculations, we estimate the Hubbard energy U in V 2 O 3 (4:20 0:05 eV). From our bulk-sensitive photoemission spectra we infer the existence of a critical probing depth for investigating electronic properties in strongly correlated solids.

Research paper thumbnail of Electronic Correlations at the α-γ Structural Phase Transition in Paramagnetic Iron

Physical Review Letters, 2011

We compute the equilibrium crystal structure and phase stability of iron at the α(bcc)-γ(fcc) pha... more We compute the equilibrium crystal structure and phase stability of iron at the α(bcc)-γ(fcc) phase transition as a function of temperature, by employing a combination of ab initio methods for calculating electronic band structures and dynamical mean-field theory. The magnetic correlation energy is found to be an essential driving force behind the α-γ structural phase transition in paramagnetic iron.

Research paper thumbnail of Nonlocal Coulomb Interactions and Metal-Insulator Transition in Ti2O3: A Cluster LDA+DMFT Approach

Physical Review Letters, 2004

We present an ab initio quantum theory of the metal-insulator transition in Ti2O3. The recently d... more We present an ab initio quantum theory of the metal-insulator transition in Ti2O3. The recently developed cluster LDA+DMFT scheme is applied to describe the many-body features of this compound. The conventional single site DMFT cannot reproduce a low temperature insulating phase for any reasonable values of the Coulomb interaction. We show that the non-local Coulomb interactions and the strong chemical bonding within Ti-Ti pair is the origin of the small gap insulating ground state of Ti2O3.

Research paper thumbnail of Mott Transition and Suppression of Orbital Fluctuations in Orthorhombic 3d1 Perovskites

Physical Review Letters, 2004

M o tt tr a n sitio n and su p p ressio n o f o rb ita l flu ctu a tio n s in o rth o rh o m b ic... more M o tt tr a n sitio n and su p p ressio n o f o rb ita l flu ctu a tio n s in o rth o rh o m b ic 3d1 p ero v sk ites

Research paper thumbnail of Hydrogenation-driven formation of local magnetic moments in FeO2Hx

Physical Review B

The electronic and magnetic properties of recently discovered new important constituent of the Ea... more The electronic and magnetic properties of recently discovered new important constituent of the Earth's lower mantle FeO2H were investigated by means of the density functional theory combined with the dynamical mean field theory (DFT+DMFT). Addition of the hydrogen to the parent FeO2 compound, which is an uncorrelated bad metal, destroys the most important ingredient of its electronic structure-O-O molecular orbitals. In effect physical properties of FeO2 and FeO2H turn to be completely different, FeO2H is a correlated metal with a mass renormalization, m * /m ∼ 1.7, and magnetic moments on Fe ions become localized with the Curie-Weiss type of uniform magnetic susceptibility.

Research paper thumbnail of Influence of Molecular Orbitals on Magnetic Properties of FeO2Hx

Molecules

Recent discoveries of various novel iron oxides and hydrides, which become stable at very high pr... more Recent discoveries of various novel iron oxides and hydrides, which become stable at very high pressure and temperature, are extremely important for geoscience. In this paper, we report the results of an investigation on the electronic structure and magnetic properties of the hydride FeO 2 H x , using density functional theory plus dynamical mean-field theory (DFT+DMFT) calculations. An increase in the hydrogen concentration resulted in the destruction of dimeric oxygen pairs and, hence, a specific band structure of FeO 2 with strongly hybridized Fe- t 2 g -O- p z anti-bonding molecular orbitals, which led to a metallic state with the Fe ions at nearly 3+. Increasing the H concentration resulted in effective mass enhancement growth which indicated an increase in the magnetic moment localization. The calculated static momentum-resolved spin susceptibility demonstrated that an incommensurate antiferromagnetic (AFM) order was expected for FeO 2 , whereas strong ferromagnetic (FM) fluct...

Research paper thumbnail of XPS evidence of degradation mechanism in СH3NH3PbI3 hybrid perovskite

Journal of Physics: Condensed Matter

The paper presents the results of measurements of XPS valence band spectra of SiO 2 /MAPbI 3 hybr... more The paper presents the results of measurements of XPS valence band spectra of SiO 2 /MAPbI 3 hybrid perovskites subjected to irradiation with visible light and annealing at an exposure of 0-1000 hours. It is found from XPS survey spectra that in both cases (irradiation and annealing) a decrease in the I:Pb ratio is observed with aging time, which unambiguously indicates PbI 2 phase separation as a photo and thermal product of degradation. The comparison of the XPS valence band spectra of irradiated and annealed perovskites with density functional theory calculations of the MAPbI 3 and PbI 2 compounds have showed a systematic decrease in the contribution of I 5p-states and allowed us to determine the threshold for degradation, which is 500 hours for light irradiation and 200 hours for annealing.

Research paper thumbnail of Electronic correlations and competing orders in multiorbital dimers: A cluster DMFT study

Physical Review B

We investigate the violation of the first Hund's rule in 4d and 5d transition metal oxides that f... more We investigate the violation of the first Hund's rule in 4d and 5d transition metal oxides that form solids of dimers. Bonding states within these dimers reduce the magnetization of such materials. We parametrize the dimer formation with realistic hopping parameters and find not only regimes, where the system behaves as a Fermi liquid or as a Peierls insulator, but also strongly correlated regions due to Hund's coupling and its competition with the dimer formation. The electronic structure is investigated using the cluster dynamical mean-field theory for a dimer in the two-plane Bethe lattice with two orbitals per site and 3/8-filling, that is three electrons per dimer. It reveals dimerantiferromagnetic order of a high-spin (double exchange) state and a low-spin (molecular orbital) state. At the crossover region we observe the suppression of long-range magnetic order, fluctuation enhancement and renormalization of electron masses. At certain interaction strengths the system becomes an incoherent antiferromagnetic metal with well defined local moments.

Research paper thumbnail of Unexpected 3+ valence of iron in FeO2, a geologically important material lying "in between" oxides and peroxides

Scientific reports, Jan 11, 2017

Recent discovery of the pyrite FeO2, which can be an important ingredient of the Earth's lowe... more Recent discovery of the pyrite FeO2, which can be an important ingredient of the Earth's lower mantle and which in particular may serve as an extra source of water in the Earth's interior, opens new perspectives for geophysics and geochemistry, but this is also an extremely interesting material from physical point of view. We found that in contrast to naive expectations Fe is nearly 3+ in this material, which strongly affects its magnetic properties and makes it qualitatively different from well known sulfide analogue - FeS2. Doping, which is most likely to occur in the Earth's mantle, makes FeO2 much more magnetic. In addition we show that unique electronic structure places FeO2 "in between" the usual dioxides and peroxides making this system interesting both for physics and solid state chemistry.

Research paper thumbnail of Magnetic properties ofFe1−xNixalloy from CPA+DMFT perspectives

Physical Review B, 2016

We use a combination of the coherent potential approximation and dynamical mean field theory to s... more We use a combination of the coherent potential approximation and dynamical mean field theory to study magnetic properties of the Fe1−xNix alloy from a first principles. Calculated uniform magnetic susceptibilities have a Curie-Weiss-like behavior and extracted effective temperatures are in agreement with the experimental results. The individual squared magnetic moments obtained as function of nickel concentration follow the same trends as experimental data. An analysis of the ionic and spin weights shows a possibility of a high-spin to intermediate-and low-spin states transitions at high temperatures.

Research paper thumbnail of Momentum-resolved spectroscopy of correlated metals: A view from dynamical mean field theory

Data Revues 16310705 V10i6 S1631070509001042, Jul 1, 2009

... E-mail addresses: jan.tomczak@polytechnique.edu (JM Tomczak), alexander.poteryaev@ polytechni... more ... E-mail addresses: jan.tomczak@polytechnique.edu (JM Tomczak), alexander.poteryaev@ polytechnique.edu (AI Poteryaev), biermann@cpht.polytechnique.fr (S. Biermann). ... Phys. 3 (2007) 168. [15] IA Nekrasov, K. Held, G. Keller, DE Kondakov, Th. ...

Research paper thumbnail of Electronic structure of CuV_2S_4

The delafossite type CuFeO2 single crystal was studied by means of x-ray emission and x-ray photo... more The delafossite type CuFeO2 single crystal was studied by means of x-ray emission and x-ray photoelectron spectroscopy. The valence state of Cu ions was found to be 1+, whereas Fe-ions were found to be trivalent in the high-spin S=5/2 state. The x-ray emission (Cu L_alpha , Fe L_alpha and O K_alpha ) and photoelectron spectra were compared to the results

Research paper thumbnail of Electronic structure of advanced materials studied by x-ray emission spectroscopy

The 17th international conference on x-ray and inner-shell processes, 1997

ABSTRACT High resolution soft x-ray emission spectroscopy with high spatial resolution is used to... more ABSTRACT High resolution soft x-ray emission spectroscopy with high spatial resolution is used to study of the electronic structure and characterize advanced materials: high-Tc superconductors, transition metal compounds, porous silicon, solid-solid buried interfaces and hard materials. In high-Tc, the main attention is focused on the analysis of oxygen-cation interactions and the determination of the location of impurity atoms. In transition metal compounds the participation of different electronic states of constitute atoms in the valence band is analyzed and correctness of LDA band structure calculations is estimated. For CuFeO2 an unusual mutual position of the Cu3d and Fe3d bands was found which is attributed to strong electron-electron correlations. In porous silicon the local structure of silicon atoms is found to depend on the type of doping of the initial Si wafer. Solid-solid buried interfaces in thin semiconducting films irradiated by eximer laser are investigated. For the hard materials boron-carbonitride a structure consisting of hexagonal lattice planes of carbon and boron nitride is proposed. © 1997 American Institute of Physics.

Research paper thumbnail of Specific heat of a binary alloy within the CPA+DMFT method

Research paper thumbnail of Dynamical mean field approach for non-collinear doped antiferromagnets

We have generalized a dynamical mean field approach in the iterative perturbation scheme (H.Kajue... more We have generalized a dynamical mean field approach in the iterative perturbation scheme (H.Kajueter, G.Kotliar, Phys.Rev.Lett.77,131 (1996)) to study the electronic structure of non-collinear magnetic states. A local approximation for the exact self-energy in d=∞ is found to be a very convenient approximation for spin-spiral magnetic configurations for real 2d- and 3d-lattices. We investigate a doped 2d-antiferromagnet in the one-band Hubbard model and show that the antiferromagnetic (AFM) state is unstable towards the formation of a spin spiral configuration. The quasiparticle peak (in the density of states) agrees well with the quantum Monte Carlo calculations. As the non-doped AFM insulator is unstable in this approach, we argue that instead of the Iterative Perturbation Theory, a more realistic description for magnetic systems is obtained with a transverse and longitudinal spin fluctuation approach which includes the Hartree-Fock terms in the ''bath`` Green-function. In...

Research paper thumbnail of Magnetostriction and ferroelectric state in AgCrS2

Journal of physics. Condensed matter : an Institute of Physics journal, Jan 30, 2015

The band structure calculations in the GGA+U approximation show the presence of additional lattic... more The band structure calculations in the GGA+U approximation show the presence of additional lattice distortions in the magnetically ordered phase of AgCrS2. The magnetostriction leads to the formation of long and short Cr-Cr bonds in the case when the respective Cr ions have the same or opposite spin projections. These changes in the Cr lattice are accompanied by distortions of the CrS6 octahedra, which in turn lead to the development of spontaneous electric polarization.

Research paper thumbnail of Combining density-functional and dynamical-mean-field theory for La1-xSrxTiO3

Physical Review B, 2000

ABSTRACT The dynamical-mean-field theory combined with the noncrossing approximation is used to s... more ABSTRACT The dynamical-mean-field theory combined with the noncrossing approximation is used to set up a scheme to study the electronic structure of strongly correlated electron systems. The noninteracting band structure is obtained from a density-functional calculation within the local-density approximation. With this method the doped Mott insulator La1-xSrxTi O3 is studied. Starting from first-principle calculations for a cubic and an orthorhombic system we determine the one-particle spectrum. Both one-particle spectra show a lower Hubbard band (seen as d1-->d0 transitions in photoemission experiments) and a quasiparticle resonance near the Fermi energy and the upper Hubbard band (d1-->d2 transitions in an inverse photoemission experiment). The upper Hubbard band develops a multipeak structure, a consequence of the consideration of all local two-particle correlations, which leads to the full multiplet structure in the atomic limit. The calculation for the orthorhombic system shows qualitative good agreement when compared with experimental photoemission spectra.

Research paper thumbnail of Valence-band spectra and electronic structure of CuFeO2

Physical Review B, 1997

... Tong-Rong Zhao Institute for Solid State Physics, University of Tokyo, 7-22-1, Roppongi, Mina... more ... Tong-Rong Zhao Institute for Solid State Physics, University of Tokyo, 7-22-1, Roppongi, Minato-ku, Tokyo 106, Japan Received 3 December 1996 ... The feed rod was suspended from the upper holder by a platinum wire and the lower seed, made from a sintered rod, was fixed ...

Research paper thumbnail of Electronic structure of superconducting inorganic polymer (SN)(x)

Physica C, 1999

... EZ Kurmaev a , AI Poteryaev a , VI Anisimov a , I. Karla b , A. Moewes c , * , B. Schneider b... more ... EZ Kurmaev a , AI Poteryaev a , VI Anisimov a , I. Karla b , A. Moewes c , * , B. Schneider b , M. Neumann b , DL Ederer d and RN Lyubovskaya e. ... The position sensitive detector is moved along the Rowland circle to the region of interest for the emission measurements. ...

Research paper thumbnail of Fermi Surface of CaVO3 perovskite: LDA+DMFT study

We present ab initio LDA+DMFT calculations of CaVO3 perovskite near Mott transition. The calculat... more We present ab initio LDA+DMFT calculations of CaVO3 perovskite near Mott transition. The calculated electronic structure and Fermi surface are in good agreement with an experimental data. The DMFT results are compared to conventional LDA band structure and an experimental data. The difference between the Fermi surfaces obtained by LDA+DMFT, LDA methods and de Haas-van Alphen data are discussed.

Research paper thumbnail of Coherent Peaks and Minimal Probing Depth in Photoemission Spectroscopy of Mott-Hubbard Systems

Physical Review Letters, 2006

We have measured hard x-ray photoemission spectra of pure vanadium sesquioxide (V 2 O 3) across i... more We have measured hard x-ray photoemission spectra of pure vanadium sesquioxide (V 2 O 3) across its metal-insulator transition. We show that, in the metallic phase, a clear correlation exists between the shakedown satellites observed in the vanadium 2p and 3p core-level spectra and the coherent peak measured at the Fermi level. Comparing experimental results and dynamical mean-field theory calculations, we estimate the Hubbard energy U in V 2 O 3 (4:20 0:05 eV). From our bulk-sensitive photoemission spectra we infer the existence of a critical probing depth for investigating electronic properties in strongly correlated solids.

Research paper thumbnail of Electronic Correlations at the α-γ Structural Phase Transition in Paramagnetic Iron

Physical Review Letters, 2011

We compute the equilibrium crystal structure and phase stability of iron at the α(bcc)-γ(fcc) pha... more We compute the equilibrium crystal structure and phase stability of iron at the α(bcc)-γ(fcc) phase transition as a function of temperature, by employing a combination of ab initio methods for calculating electronic band structures and dynamical mean-field theory. The magnetic correlation energy is found to be an essential driving force behind the α-γ structural phase transition in paramagnetic iron.

Research paper thumbnail of Nonlocal Coulomb Interactions and Metal-Insulator Transition in Ti2O3: A Cluster LDA+DMFT Approach

Physical Review Letters, 2004

We present an ab initio quantum theory of the metal-insulator transition in Ti2O3. The recently d... more We present an ab initio quantum theory of the metal-insulator transition in Ti2O3. The recently developed cluster LDA+DMFT scheme is applied to describe the many-body features of this compound. The conventional single site DMFT cannot reproduce a low temperature insulating phase for any reasonable values of the Coulomb interaction. We show that the non-local Coulomb interactions and the strong chemical bonding within Ti-Ti pair is the origin of the small gap insulating ground state of Ti2O3.

Research paper thumbnail of Mott Transition and Suppression of Orbital Fluctuations in Orthorhombic 3d1 Perovskites

Physical Review Letters, 2004

M o tt tr a n sitio n and su p p ressio n o f o rb ita l flu ctu a tio n s in o rth o rh o m b ic... more M o tt tr a n sitio n and su p p ressio n o f o rb ita l flu ctu a tio n s in o rth o rh o m b ic 3d1 p ero v sk ites