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Generally, lattice distortions play a key role in determining the electronic ground states of materials. Although it is well known that trigonal distortions are generic to most two dimensional transition metal dichalcogenides, the impact of this structural distortion on the electronic structure and topological properties has not been understood conclusively. Here, by using a combination of polarization dependent X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) and atomic multiplet cluster calculations, we have investigated the electronic structure of titanium dichalcogenides TiX2 (X = S, Se, Te), where the magnitude of the trigonal distortion increase monotonically from S to Se and Te. Our results reveal the presence of an anomalously large crystal field splitting. This unusual kind of crystal field splitting is likely responsible for the unconventional electronic structure of TiX2 compounds and ultimately controls the degree of the electronic phase protection. Our findings also indicate the drawback of the distorted crystal field picture in explaining the observed electronic ground state and emphasize the key importance of trigonal symmetry, metal-ligand hybridization and electron-electron correlations in defining the electronic structures at the Fermi energy.

Generally, lattice distortions play a key role in determining the electronic ground states of materials. Although it is well known that trigonal distortions are generic to most two dimensional transition metal dichalcogenides, the impact of this structural distortion on the electronic structure and topological properties has not been understood conclusively. Here, by using a combination of polarization dependent X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) and atomic multiplet cluster calculations, we have investigated the electronic structure of titanium dichalcogenides TiX2 (X = S, Se, Te), where the magnitude of the trigonal distortion increase monotonically from S to Se and Te. Our results reveal the presence of an anomalously large crystal field splitting. This unusual kind of crystal field splitting is likely responsible for the unconventional electronic structure of TiX2 compounds and ultimately controls the degree of the electronic phase protection. Our findings also indicate the drawback of the distorted crystal field picture in explaining the observed electronic ground state and emphasize the key importance of trigonal symmetry, metal-ligand hybridization and electron-electron correlations in defining the electronic structures at the Fermi energy.

We present magnetic measurements on Nd2NiMnO6 which exhibits a well-known insulating paramagnetic state to an insulating ferromagnetic state transition when cooled below 200 K. Beyond this basic fact, there is a great deal of diversity in the reported magnetic properties and interpretation of specific anomalies observed in the magnetic data of this compound below the Curie temperature. We address specifically two anomalies discussed in the past, namely, a spin-glass like behavior observed in some samples near 100 K and a downturn in the magnetization with a lowering of the temperature below approximately 50 K. We show for the first time that the application of an increasing magnetic field can systematically change the low-temperature behavior to make the down-turn in the magnetization into an upturn. With the help of first principle calculations and extensive simulations along with our experimental observations, we provide a microscopic understanding of all magnetic properties observed in this interesting system to point out that the glassiness around 100 K is absent in well-ordered samples and that the low-temperature magnetic anomaly below 50 K is a consequence of a ferromagnetic coupling of the Nd spin moments with the spin of the Ni-Mn ordered sublattice without giving rise to any ordering of the Nd sublattice that remains paramagnetic, contrary to earlier claims. We explain this counter-intuitive interpretation of a ferromagnetic coupling of Nd spins with Ni-Mn spin giving rise to a decrease in the total magnetic moment by noting the less than half-filled 4f occupation of Nd that ensures orbital and spin moments of Nd to be opposite to each other due to the spin-orbit coupling. Since the ground state total magnetic moment of Nd has a contribution from the orbital moment, that is larger than the spin moment, the total moment of Nd is indeed pointing in a direction opposite to the direction of spin moments of the Ni-Mn sublattice as a consequence of the ferromagn

We investigate [Formula: see text]/[Formula: see text] superlattices in which we observe a full electron transfer at the interface from Ir to Ni, triggering a massive structural and electronic reconstruction. Through experimental characterization and first-principles calculations, we determine that a large crystal field splitting from the distorted interfacial [Formula: see text] octahedra surprisingly dominates over the spin-orbit coupling and together with the Hund's coupling results in the high-spin (S = 1) configurations on both the Ir and Ni sites. This demonstrates the power of interfacial charge transfer in coupling lattice, charge, orbital, and spin degrees of freedom, opening fresh avenues of investigation of quantum states in oxide superlattices.

We investigate [Formula: see text]/[Formula: see text] superlattices in which we observe a full electron transfer at the interface from Ir to Ni, triggering a massive structural and electronic reconstruction. Through experimental characterization and first-principles calculations, we determine that a large crystal field splitting from the distorted interfacial [Formula: see text] octahedra surprisingly dominates over the spin-orbit coupling and together with the Hund's coupling results in the high-spin (S = 1) configurations on both the Ir and Ni sites. This demonstrates the power of interfacial charge transfer in coupling lattice, charge, orbital, and spin degrees of freedom, opening fresh avenues of investigation of quantum states in oxide superlattices.

We investigate [Formula: see text]/[Formula: see text] superlattices in which we observe a full electron transfer at the interface from Ir to Ni, triggering a massive structural and electronic reconstruction. Through experimental characterization and first-principles calculations, we determine that a large crystal field splitting from the distorted interfacial [Formula: see text] octahedra surprisingly dominates over the spin-orbit coupling and together with the Hunds coupling results in the high-spin (S = 1) configurations on both the Ir and Ni sites. This demonstrates the power of interfacial charge transfer in coupling lattice, charge, orbital, and spin degrees of freedom, opening fresh avenues of investigation of quantum states in oxide superlattices.

We present magnetic measurements on Nd2NiMnO6 which exhibits a well-known insulating paramagnetic state to an insulating ferromagnetic state transition when cooled below 200 K. Beyond this basic fact, there is a great deal of diversity in the reported magnetic properties and interpretation of specific anomalies observed in the magnetic data of this compound below the Curie temperature. We address specifically two anomalies discussed in the past, namely, a spin-glass like behavior observed in some samples near 100 K and a downturn in the magnetization with a lowering of the temperature below approximately 50 K. We show for the first time that the application of an increasing magnetic field can systematically change the low-temperature behavior to make the down-turn in the magnetization into an upturn. With the help of first principle calculations and extensive simulations along with our experimental observations, we provide a microscopic understanding of all magnetic properties observed in this interesting system to point out that the glassiness around 100 K is absent in well-ordered samples and that the low-temperature magnetic anomaly below 50 K is a consequence of a ferromagnetic coupling of the Nd spin moments with the spin of the Ni-Mn ordered sublattice without giving rise to any ordering of the Nd sublattice that remains paramagnetic, contrary to earlier claims. We explain this counter-intuitive interpretation of a ferromagnetic coupling of Nd spins with Ni-Mn spin giving rise to a decrease in the total magnetic moment by noting the less than half-filled 4f occupation of Nd that ensures orbital and spin moments of Nd to be opposite to each other due to the spin-orbit coupling. Since the ground state total magnetic moment of Nd has a contribution from the orbital moment, that is larger than the spin moment, the total moment of Nd is indeed pointing in a direction opposite to the direction of spin moments of the Ni-Mn sublattice as a consequence of the ferromagn, Funding Agencies:Department of Science and Technology, Government of India Swedish Research Council (VR) through the Swedish Energy Agency (STEM) P46561-1 2016-04524 2013-08316 Indo-U.S. Joint Center for Rational Control of Functional Oxides under Indo-U.S. Science and Technology Forum US Department of Energy, Office of Science DE-AC02-06CH11357 eSSENCE STandUPP Jamsetji Tata Trust

La2NiMnO6 has been reported to exhibit a paramagnetic to ferromagnetic transition with a transition temperature of similar to 260 K. However, most of its magnetic properties, such as the saturation magnetization and even the transition temperature, appear to vary considerably among different reports. This is possibly because the crystallographic structure as well as the extent of the anti-site disorder (ASD) at the Ni/Mn sites are strongly influenced by the choice of synthesis routes. There are diverse reports connecting the extent of ASD to the valencies of Ni and Mn ions, such as Ni2+-Mn4+ and Ni3+-Mn3+, including suggestions of thermally induced valence transitions. Consequently, these reports arrive at very different conclusions on the mechanism behind the magnetic properties of La2NiMnO6. To address the correlation between ASD and valency, we have carried out a comparative study of two monoclinic La2NiMnO6 polycrystals with different degrees of ASD. Using a combination of x-ray absorption spectroscopy, x-raymagnetic circular dichroism, andmagnetometry, we conclude that the valency of the transition metal ions, and the transition temperature, are insensitive to the extent of ASD. However, we find the magnetic moment decreases strongly with an increasing ASD. We attribute this effect to the introduction of antiferromagnetic interactions in the anti-site disordered regions.

A novel core-shell design for nano-structured electrode materials is introduced for realizing cost-effective and high-performance supercapacitors. In the proposed core-shell design, thin shell-layers of highly pseudo-capacitive materials provide the platform for surface or near-surface-based faradaic and non-faradaic reactions together with shortened ion-diffusion path facilitating fast-ion intercalation and deintercalation processes. The highly-conducting core serves as highway for fast electron transfer toward current collectors, improving both energy and power performance characteristics of the core-shell structure in relation to pristine component materials. Furthermore, use of carbon (C)-based materials as a shell layer in either electrode not only enhances capacitive performance through double-layer formation but also provides enough mechanical strength to sustain volume changes in the core material during long-cycling of the supercapacitor improving its cycle life. In order to enhance electrochemical performance in terms of specific capacitance and rate capability via core-shell architecture and nano-structuring, an asymmetric supercapacitor (ASC) is assembled using ZnO/alpha-Fe2O3 and ZnO/C core-shell nanorods as respective negative and positive electrodes. The ASC exhibits a specific capacitance of similar to 115 F/g at a scan rate of 10 mV/s in a potential window as large as 1.8 V with a response time as short as 39 ms and retains more than 80% of its initial capacitance after 4000 cycles. Interestingly, the ASC can deliver an energy density of similar to 41 Wh/kg and a power density of similar to 7 kW/kg that are significantly higher than those reported hitherto for iron-oxide-based ASCs.

A novel core-shell design for nano-structured electrode materials is introduced for realizing cost-effective and high-performance supercapacitors. In the proposed core-shell design, thin shell-layers of highly pseudo-capacitive materials provide the platform for surface or near-surface-based faradaic and non-faradaic reactions together with shortened ion-diffusion path facilitating fast-ion intercalation and deintercalation processes. The highly-conducting core serves as highway for fast electron transfer toward current collectors, improving both energy and power performance characteristics of the core-shell structure in relation to pristine component materials. Furthermore, use of carbon (C)-based materials as a shell layer in either electrode not only enhances capacitive performance through double-layer formation but also provides enough mechanical strength to sustain volume changes in the core material during long-cycling of the supercapacitor improving its cycle life. In order to enhance electrochemical performance in terms of specific capacitance and rate capability via core-shell architecture and nano-structuring, an asymmetric supercapacitor (ASC) is assembled using ZnO/alpha-Fe2O3 and ZnO/C core-shell nanorods as respective negative and positive electrodes. The ASC exhibits a specific capacitance of similar to 115 F/g at a scan rate of 10 mV/s in a potential window as large as 1.8 V with a response time as short as 39 ms and retains more than 80% of its initial capacitance after 4000 cycles. Interestingly, the ASC can deliver an energy density of similar to 41 Wh/kg and a power density of similar to 7 kW/kg that are significantly higher than those reported hitherto for iron-oxide-based ASCs.

A novel core-shell design for nano-structured electrode materials is introduced for realizing cost-effective and high-performance supercapacitors. In the proposed core-shell design, thin shell-layers of highly pseudo-capacitive materials provide the platform for surface or near-surface-based faradaic and non-faradaic reactions together with shortened ion-diffusion path facilitating fast-ion intercalation and deintercalation processes. The highly-conducting core serves as highway for fast electron transfer toward current collectors, improving both energy and power performance characteristics of the core-shell structure in relation to pristine component materials. Furthermore, use of carbon (C)-based materials as a shell layer in either electrode not only enhances capacitive performance through double-layer formation but also provides enough mechanical strength to sustain volume changes in the core material during long-cycling of the supercapacitor improving its cycle life. In order to enhance electrochemical performance in terms of specific capacitance and rate capability via core-shell architecture and nano-structuring, an asymmetric supercapacitor (ASC) is assembled using ZnO/alpha-Fe2O3 and ZnO/C core-shell nanorods as respective negative and positive electrodes. The ASC exhibits a specific capacitance of similar to 115 F/g at a scan rate of 10 mV/s in a potential window as large as 1.8 V with a response time as short as 39 ms and retains more than 80% of its initial capacitance after 4000 cycles. Interestingly, the ASC can deliver an energy density of similar to 41 Wh/kg and a power density of similar to 7 kW/kg that are significantly higher than those reported hitherto for iron-oxide-based ASCs.

A novel core-shell design for nano-structured electrode materials is introduced for realizing cost-effective and high-performance supercapacitors. In the proposed core-shell design, thin shell-layers of highly pseudo-capacitive materials provide the platform for surface or near-surface-based faradaic and non-faradaic reactions together with shortened ion-diffusion path facilitating fast-ion intercalation and deintercalation processes. The highly-conducting core serves as highway for fast electron transfer toward current collectors, improving both energy and power performance characteristics of the core-shell structure in relation to pristine component materials. Furthermore, use of carbon (C)-based materials as a shell layer in either electrode not only enhances capacitive performance through double-layer formation but also provides enough mechanical strength to sustain volume changes in the core material during long-cycling of the supercapacitor improving its cycle life. In order to enhance electrochemical performance in terms of specific capacitance and rate capability via core-shell architecture and nano-structuring, an asymmetric supercapacitor (ASC) is assembled using ZnO/alpha-Fe2O3 and ZnO/C core-shell nanorods as respective negative and positive electrodes. The ASC exhibits a specific capacitance of similar to 115 F/g at a scan rate of 10 mV/s in a potential window as large as 1.8 V with a response time as short as 39 ms and retains more than 80% of its initial capacitance after 4000 cycles. Interestingly, the ASC can deliver an energy density of similar to 41 Wh/kg and a power density of similar to 7 kW/kg that are significantly higher than those reported hitherto for iron-oxide-based ASCs.

A novel core-shell design for nano-structured electrode materials is introduced for realizing cost-effective and high-performance supercapacitors. In the proposed core-shell design, thin shell-layers of highly pseudo-capacitive materials provide the platform for surface or near-surface-based faradaic and non-faradaic reactions together with shortened ion-diffusion path facilitating fast-ion intercalation and deintercalation processes. The highly-conducting core serves as highway for fast electron transfer toward current collectors, improving both energy and power performance characteristics of the core-shell structure in relation to pristine component materials. Furthermore, use of carbon (C)-based materials as a shell layer in either electrode not only enhances capacitive performance through double-layer formation but also provides enough mechanical strength to sustain volume changes in the core material during long-cycling of the supercapacitor improving its cycle life. In order to enhance electrochemical performance in terms of specific capacitance and rate capability via core-shell architecture and nano-structuring, an asymmetric supercapacitor (ASC) is assembled using ZnO/alpha-Fe2O3 and ZnO/C core-shell nanorods as respective negative and positive electrodes. The ASC exhibits a specific capacitance of similar to 115 F/g at a scan rate of 10 mV/s in a potential window as large as 1.8 V with a response time as short as 39 ms and retains more than 80% of its initial capacitance after 4000 cycles. Interestingly, the ASC can deliver an energy density of similar to 41 Wh/kg and a power density of similar to 7 kW/kg that are significantly higher than those reported hitherto for iron-oxide-based ASCs.

We have revisited the valence band electronic structure of NiO by means of hard x-ray photoemission spectroscopy (HAXPES) together with theoretical calculations using both the GW method and the local density approximation + dynamical mean-field theory (LDA+DMFT) approaches. The effective impurity problem in DMFT is solved through the exact diagonalization (ED) method. We show that the LDA+DMFT method in conjunction with the standard fully localized limit (FLL) and around mean field (AMF) double-counting alone cannot explain all the observed structures in the HAXPES spectra. GW corrections are required for the O bands and Ni-s and p derived states to properly position their binding energies. Our results establish that a combination of the GW and DMFT methods is necessary for correctly describing the electronic structure of NiO in a proper ab initio framework. We also demonstrate that the inclusion of photoionization cross section is crucial to interpret the HAXPES spectra of NiO. We argue that our conclusions are general and that the here suggested approach is appropriate for any complex transition metal oxide., QC 20160720

Using hard x-ray photoelectron spectroscopywith variable photon energy (2-8 keV), we address the distribution of charge carriers in the prototypical LaAlO3 (LAO) and SrTiO3 (STO) oxide heterostructures with high carrier densities (10(17) cm(-2)). Our results demonstrate the presence of two distinct charge distributions in this system: one tied to the interface with a similar to 1-nm width and similar to 2-5 x 10(14)-cm(-2) carrier concentration, while the other appears distributed nearly homogeneously through the bulk of STO corresponding to a much larger carrier contribution. Our results also establish bimodal oxygen vacancies, namely on top of LAO and throughout STO, quantitatively establishing these as the origin of the observed bimodal depth distribution of charge carriers in these highly doped sample.

We have revisited the valence band electronic structure of NiO by means of hard x-ray photoemission spectroscopy (HAXPES) together with theoretical calculations using both the GW method and the local density approximation + dynamical mean-field theory (LDA+DMFT) approaches. The effective impurity problem in DMFT is solved through the exact diagonalization (ED) method. We show that the LDA+DMFT method in conjunction with the standard fully localized limit (FLL) and around mean field (AMF) double-counting alone cannot explain all the observed structures in the HAXPES spectra. GW corrections are required for the O bands and Ni-s and p derived states to properly position their binding energies. Our results establish that a combination of the GW and DMFT methods is necessary for correctly describing the electronic structure of NiO in a proper ab initio framework. We also demonstrate that the inclusion of photoionization cross section is crucial to interpret the HAXPES spectra of NiO. We argue that our conclusions are general and that the here suggested approach is appropriate for any complex transition metal oxide.

A combination of measurements using photoelectron spectroscopy and calculations using density functional theory (DFT) was applied to compare the detailed electronic structure of the organolead halide perovskites CH3NH3PbI3 and CH3NH3PbBr3. These perovskite materials are used to absorb light in mesoscopic and planar heterojunction solar cells. The Pb 4f core level is investigated to get insight into the chemistry of the two materials. Valence level measurments are also included showing a shift of the valence band edges where there is a higher binding energy of the edge for the CH3NH3PbBr3 perovskite. These changes are supported by the theoretical calculations which indicate that the differences in electronic structure are mainly caused by the nature of the halide ion rather than structural differences. The combination of photoelectron spectroscopy measurements and electronic structure calculations is essential to disentangle how the valence band edge in organolead halide perovskites is governed by the intrinsic difference in energy levels of the halide ions from the influence of chemical bonding.

Several scientific issues concerning the latest generation read heads for magnetic storage devices, based on CoFeB/MgO/CoFeBmagnetic tunnel junctions (MTJs) are known to be controversial, including such fundamental questions as to the behavior and the role of B in optimizing the physical properties of these devices. Quantitatively establishing the internal structures of several such devices with different annealing conditions using hard x-ray photoelectron spectroscopy, we resolve these controversies and establish that the B diffusion is controlled by the capping Ta layer, though Ta is physically separated from the layer with B by several nanometers. While explaining this unusual phenomenon, we also provide insight into why the tunneling magnetoresistance (TMR) is optimized at an intermediate annealing temperature, relating it to B diffusion, coupled with our studies based on x-ray diffraction and magnetic studies., QC 20150507

A combination of measurements using photoelectron spectroscopy and calculations using density functional theory (DFT) was applied to compare the detailed electronic structure of the organolead halide perovskites CH3NH3PbI3 and CH3NH3PbBr3. These perovskite materials are used to absorb light in mesoscopic and planar heterojunction solar cells. The Pb 4f core level is investigated to get insight into the chemistry of the two materials. Valence level measurments are also included showing a shift of the valence band edges where there is a higher binding energy of the edge for the CH3NH3PbBr3 perovskite. These changes are supported by the theoretical calculations which indicate that the differences in electronic structure are mainly caused by the nature of the halide ion rather than structural differences. The combination of photoelectron spectroscopy measurements and electronic structure calculations is essential to disentangle how the valence band edge in organolead halide perovskites is governed by the intrinsic difference in energy levels of the halide ions from the influence of chemical bonding., AuthorCount:14

The electronic structure of the (La0.8Sr0.2)0.98Mn1−xCrxO3 model series (x = 0, 0.05, or 0.1) was measured using soft X-ray synchrotron radiation at room and elevated temperature. O K-edge nearedge X-ray absorption fine structure (NEXAFS) spectra showed that low-level chromium substitution of (La,Sr)MnO3 resulted in lowered hybridisation between O 2p orbitals and M 3d and M 4sp valance orbitals. Mn L3-edge resonant photoemission spectroscopy measurements indicated lowered Mn 3d-O 2p hybridisation with chromium substitution. Deconvolution of O K-edge NEXAFS spectra took into account the effects of exchange and crystal field splitting and included a novel approach whereby the pre-peak region was described using the nominally filled t2g ↑ state. 10% chromium substitution resulted in a 0.17 eV lowering in the energy of the t2g ↑ state, which appears to provide an explanation for the 0.15 eV rise in activation energy for the oxygen reduction reaction, while decreased overlap between hybrid O 2p-Mn 3d states was in qualitative agreement with lowered electronic conductivity. An orbital-level understanding of the thermodynamically predicted solid oxide fuel cell cathode poisoning mechanism involving low-level chromium substitution on the B-site of (La,Sr)MnO3 is presented.

The electronic structure of the (La0.8Sr0.2)0.98Mn1−xCrxO3 model series (x = 0, 0.05, or 0.1) was measured using soft X-ray synchrotron radiation at room and elevated temperature. O K-edge nearedge X-ray absorption fine structure (NEXAFS) spectra showed that low-level chromium substitution of (La,Sr)MnO3 resulted in lowered hybridisation between O 2p orbitals and M 3d and M 4sp valance orbitals. Mn L3-edge resonant photoemission spectroscopy measurements indicated lowered Mn 3d-O 2p hybridisation with chromium substitution. Deconvolution of O K-edge NEXAFS spectra took into account the effects of exchange and crystal field splitting and included a novel approach whereby the pre-peak region was described using the nominally filled t2g ↑ state. 10% chromium substitution resulted in a 0.17 eV lowering in the energy of the t2g ↑ state, which appears to provide an explanation for the 0.15 eV rise in activation energy for the oxygen reduction reaction, while decreased overlap between hybrid O 2p-Mn 3d states was in qualitative agreement with lowered electronic conductivity. An orbital-level understanding of the thermodynamically predicted solid oxide fuel cell cathode poisoning mechanism involving low-level chromium substitution on the B-site of (La,Sr)MnO3 is presented.

The electronic structure of the (La0.8Sr0.2)0.98Mn1−xCrxO3 model series (x = 0, 0.05, or 0.1) was measured using soft X-ray synchrotron radiation at room and elevated temperature. O K-edge nearedge X-ray absorption fine structure (NEXAFS) spectra showed that low-level chromium substitution of (La,Sr)MnO3 resulted in lowered hybridisation between O 2p orbitals and M 3d and M 4sp valance orbitals. Mn L3-edge resonant photoemission spectroscopy measurements indicated lowered Mn 3d-O 2p hybridisation with chromium substitution. Deconvolution of O K-edge NEXAFS spectra took into account the effects of exchange and crystal field splitting and included a novel approach whereby the pre-peak region was described using the nominally filled t2g ↑ state. 10% chromium substitution resulted in a 0.17 eV lowering in the energy of the t2g ↑ state, which appears to provide an explanation for the 0.15 eV rise in activation energy for the oxygen reduction reaction, while decreased overlap between hybrid O 2p-Mn 3d states was in qualitative agreement with lowered electronic conductivity. An orbital-level understanding of the thermodynamically predicted solid oxide fuel cell cathode poisoning mechanism involving low-level chromium substitution on the B-site of (La,Sr)MnO3 is presented.

The electronic structure of the (La0.8Sr0.2)0.98Mn1−xCrxO3 model series (x = 0, 0.05, or 0.1) was measured using soft X-ray synchrotron radiation at room and elevated temperature. O K-edge nearedge X-ray absorption fine structure (NEXAFS) spectra showed that low-level chromium substitution of (La,Sr)MnO3 resulted in lowered hybridisation between O 2p orbitals and M 3d and M 4sp valance orbitals. Mn L3-edge resonant photoemission spectroscopy measurements indicated lowered Mn 3d-O 2p hybridisation with chromium substitution. Deconvolution of O K-edge NEXAFS spectra took into account the effects of exchange and crystal field splitting and included a novel approach whereby the pre-peak region was described using the nominally filled t2g ↑ state. 10% chromium substitution resulted in a 0.17 eV lowering in the energy of the t2g ↑ state, which appears to provide an explanation for the 0.15 eV rise in activation energy for the oxygen reduction reaction, while decreased overlap between hybrid O 2p-Mn 3d states was in qualitative agreement with lowered electronic conductivity. An orbital-level understanding of the thermodynamically predicted solid oxide fuel cell cathode poisoning mechanism involving low-level chromium substitution on the B-site of (La,Sr)MnO3 is presented.

Tailoring transport properties of strongly correlated electron systems in a controlled fashion counts among the dreams of materials scientists. In copper oxides, vary- ing the carrier concentration is a tool to obtain high- temperature superconducting phases. In manganites, dop- ing results in exotic physics such as insulator-metal tran- sitions (IMT), colossal magnetoresistance (CMR), orbital- or charge-ordered (CO) or charge-disproportionate (CD) states. In most oxides, antiferromagnetic order and CD phase is asssociated with insulating behavior. Here we re- port the realization of a unique physical state that can be induced by Mo doping in LaFeO3: the resulting metallic state is a site-selective Mott insulator where itinerant elec- trons evolving on low-energy Mo states coexist with local- ized carriers on the Fe sites. In addition, a local breathing- type lattice distortion induces charge disproportionation on the latter, without destroying the antiferromagnetic order. A state, combining antiferromangetism, metallic- ity and CD phenomena is rather rare in oxides and have utmost significance for future antiferromagnetic memory devices.

Tailoring transport properties of strongly correlated electron systems in a controlled fashion counts among the dreams of materials scientists. In copper oxides, vary- ing the carrier concentration is a tool to obtain high- temperature superconducting phases. In manganites, dop- ing results in exotic physics such as insulator-metal tran- sitions (IMT), colossal magnetoresistance (CMR), orbital- or charge-ordered (CO) or charge-disproportionate (CD) states. In most oxides, antiferromagnetic order and CD phase is asssociated with insulating behavior. Here we re- port the realization of a unique physical state that can be induced by Mo doping in LaFeO3: the resulting metallic state is a site-selective Mott insulator where itinerant elec- trons evolving on low-energy Mo states coexist with local- ized carriers on the Fe sites. In addition, a local breathing- type lattice distortion induces charge disproportionation on the latter, without destroying the antiferromagnetic order. A state, combining antiferromangetism, metallic- ity and CD phenomena is rather rare in oxides and have utmost significance for future antiferromagnetic memory devices.

Tailoring transport properties of strongly correlated electron systems in a controlled fashion counts among the dreams of materials scientists. In copper oxides, vary- ing the carrier concentration is a tool to obtain high- temperature superconducting phases. In manganites, dop- ing results in exotic physics such as insulator-metal tran- sitions (IMT), colossal magnetoresistance (CMR), orbital- or charge-ordered (CO) or charge-disproportionate (CD) states. In most oxides, antiferromagnetic order and CD phase is asssociated with insulating behavior. Here we re- port the realization of a unique physical state that can be induced by Mo doping in LaFeO3: the resulting metallic state is a site-selective Mott insulator where itinerant elec- trons evolving on low-energy Mo states coexist with local- ized carriers on the Fe sites. In addition, a local breathing- type lattice distortion induces charge disproportionation on the latter, without destroying the antiferromagnetic order. A state, combining antiferromangetism, metallic- ity and CD phenomena is rather rare in oxides and have utmost significance for future antiferromagnetic memory devices.

Tailoring transport properties of strongly correlated electron systems in a controlled fashion counts among the dreams of materials scientists. In copper oxides, vary- ing the carrier concentration is a tool to obtain high- temperature superconducting phases. In manganites, dop- ing results in exotic physics such as insulator-metal tran- sitions (IMT), colossal magnetoresistance (CMR), orbital- or charge-ordered (CO) or charge-disproportionate (CD) states. In most oxides, antiferromagnetic order and CD phase is asssociated with insulating behavior. Here we re- port the realization of a unique physical state that can be induced by Mo doping in LaFeO3: the resulting metallic state is a site-selective Mott insulator where itinerant elec- trons evolving on low-energy Mo states coexist with local- ized carriers on the Fe sites. In addition, a local breathing- type lattice distortion induces charge disproportionation on the latter, without destroying the antiferromagnetic order. A state, combining antiferromangetism, metallic- ity and CD phenomena is rather rare in oxides and have utmost significance for future antiferromagnetic memory devices.

Tailoring transport properties of strongly correlated electron systems in a controlled fashion counts among the dreams of materials scientists. In copper oxides, vary- ing the carrier concentration is a tool to obtain high- temperature superconducting phases. In manganites, dop- ing results in exotic physics such as insulator-metal tran- sitions (IMT), colossal magnetoresistance (CMR), orbital- or charge-ordered (CO) or charge-disproportionate (CD) states. In most oxides, antiferromagnetic order and CD phase is asssociated with insulating behavior. Here we re- port the realization of a unique physical state that can be induced by Mo doping in LaFeO3: the resulting metallic state is a site-selective Mott insulator where itinerant elec- trons evolving on low-energy Mo states coexist with local- ized carriers on the Fe sites. In addition, a local breathing- type lattice distortion induces charge disproportionation on the latter, without destroying the antiferromagnetic order. A state, combining antiferromangetism, metallic- ity and CD phenomena is rather rare in oxides and have utmost significance for future antiferromagnetic memory devices.