We present an analysis of the polymorphic energy ordering and properties of the rock salt and zincblende structures of manganese oxide using fixed node diffusion Monte Carlo (DMC). Manganese oxide is a correlated, antiferromagnetic material that has proven to be challenging to model from first principles across a variety of approaches. Unlike conventional density functional theory and some hybrid functionals, fixed node diffusion Monte Carlo finds the rock salt structure to be more stable than the zincblende structure, and thus recovers the correct energy ordering. Analysis of the site-resolved charge fluctuations of the wave functions according to DMC and other electronic structure descriptions give insights into elements that are missing in other theories. While the calculated band gaps within DMC are in agreement with predictions that the zincblende polymorph has a lower band gap, the gaps themselves overestimate reported experimental values.
Using first-principles calculations in combination with special quasirandom structure and occupation control matrix methods, we study the magnetic ordering and the effect of pressure on manganese sulfide polymorphs. At ambient conditions, MnS is commonly observed in paramagnetic rock-salt structure, but as temperature decreases at constant pressure it becomes antiferromagnetic. On the other hand, at room temperature MnS has shown to undergo structural transformations as pressure increases. Here, we show that our approach involving the ordering/disordering of the local magnetic moments in addit…
Manganese oxide nanosheets were synthesized using liquid phase exfoliation that achieved suspensions in isopropanol with concentrations of up to 0.45 mg/ml. A study of solubility parameters showed that the exfoliation was optimum in DMF followed by isopropanol and diethylene glycol. Isopropanol was the solvent of choice due to its environmentally friendly nature and ease of use for further processing. The 2D hybrid was synthesized in isopropanol suspensions with concentrations of up to 0.5 mg/ml and demonstrated stability against reaggregation for up to six months. The coexfoliation was found …
X-ray amorphous manganese oxides were prepared by reduction of sodium permanganate by lithium iodide in aqueous medium (MnOx-I) and by decomposition of manganese carbonate at moderate temperature (MnOx-C). TEM showed that these materials are not amorphous, but nanostructured, with a prominent spinel substructure in MnOx-C. These materials intercalate lithium with capacities up to 200 mAh/g at first cycle (potential window 1.8-4.3 V) and 175 mAh/g at 100th cycle. Best performances for MnOx-C are obtained with cobalt doping. Potential electrochemical spectroscopy shows that the initial discharge…
Atom probe tomography is routinely used for the characterisation of materials microstructures usually assuming that the microstructure is unaltered by the analysis. When analysing ionic conductors, however, gradients in the chemical potential and the electric field penetrating dielectric atom probe specimens can cause significant ionic mobility. While ionic mobility is undesired when aiming for materials characterisation it offers a strategy to manipulate materials directly in-situ in the atom probe. Here, we present experimental results on the analysis of the ionic conductor Lithium-Manganese…
Two-dimensional manganese oxide layers have been grown on Pd(100) and have been characterized by scanning tunnelling microscopy (STM), low-energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS). The complex surface phase diagram of MnOx on Pd(100) is reported, where nine different novel Mn oxide phases have been detected as a function of the chemical potential of oxygen mO. Three regions of the chemical potential of oxygen can be identified, in which structurally related oxide phases are formed, often in coexistence at the surface. The different regions of mO are reflect…
The structure and magnetic properties of oligonuclear manganese complex [Mn(hfa)2cpo]2 (where hfa is hexafluoroacetylacetonate dehydrate and cpo is 4-cyanopyridine-N-oxide) are presented. In the unit cell, the dinuclear molecules are well isolated from each other. The non-monotonous dependence of magnetic susceptibility is explained in terms of the hierarchy of exchange parameters by using exact diagonalization. The thermodynamic behavior of pure cpo and [Mn(hfa)2(cpo)]2 is simulated numerically in a dimer approximation by an extrapolation to spin S = 5/2. The Mn-Mn exchange integral is evalua…
The electronic structure is found to be understandable in terms of free-atom term values and universal interorbital coupling parameters, since self-consistent tight-binding calculations indicate that Coulomb shifts of the d-state energies are small. Special-point averages over the bands are seen to be equivalent to treatment of local octahedral clusters. The cohesive energy per manganese for MnO, Mn2O3, and MnO2, in which manganese exists in valence states Mn2+, Mn3+, and Mn4+, is very nearly the same and dominated by the transfer of manganese s electrons to oxygen p states. There are small co…
We performed a systematic study of soft X-ray absorption spectroscopy in various manganese oxides and fluorides. Both Mn L-edges and ligand (O and F) K-edges are presented and compared with each other. Despite the distinct crystal structure and covalent/ionic nature in different systems, the Mn-L spectra fingerprint the Mn valence and spin states through spectral lineshape and energy position consistently and evidently. The clear O- and F- K pre-edge features in our high resolution spectra enable a quantitative definition of the molecular orbital diagram with different Mn valence. In addition,…
Effectiveness of galaxite (Al2O3MnO) and manganese oxide (MnO2) in nucleating acicular ferrite was demonstrated in a steel with composition of Fe-13.92Mn-4.53Al-1.28Si-0.11C. The hot rolled and quenched steel had a duplex microstructure of delta-ferrite and partially transformed austenite. Thermal treatments were used to manipulate the concentration and type of oxides and the ferrite plate density was found to correlate with inclusions of low misfit. Both bainitic and acicular ferrite were observed and the prior austenite had a grain diameter of 16.5 micrometers. Upon tensile testing the retai…
Unraveling the atomistic and the electronic structure of solid-liquid interfaces is the key to the design of new materials for many important applications, from heterogeneous catalysis to battery technology. Density functional theory (DFT) calculations can in principle provide a reliable description of such interfaces, but the high computational costs severely restrict the accessible time and length scales. Here, we report machine learning-driven simulations of various interfaces between water and lithium manganese oxide (Li$_x$Mn$_2$O$_4$), an important electrode material in lithium ion batte…
Through direct nanoparticle nucleation and growth on nitrogen doped, reduced graphene oxide sheets and cation substitution of spinel Co3O4 nanoparticles, a manganese-cobalt spinel MnCo2O4/graphene hybrid was developed as a highly efficient electrocatalyst for oxygen reduction reaction (ORR) in alkaline conditions. Electrochemical and X-ray near edge structure (XANES) investigations revealed that the nucleation and growth method for forming inorganic-nanocarbon hybrid results in covalent coupling between spinel oxide nanoparticles and N-doped reduced graphene oxide (N-rmGO) sheets. Carbon K-edg…
Ferroelectric oxides have attracted much attention due to their wide range of applications, especially in electronic devices such as nonvolatile memories and tunnel junctions. As a result, the monolithic integration of these materials into silicon technology and its nanostructuration to develop alternative cost-effective processes are among the central points in current technology. In this work, we used a chemical route to obtain nanowire thin films of a novel Sr1+δMn8O16 (SMO) hollandite-type manganese oxide on silicon. Scanning transmission electron microscopy combined with crystallographic …
The enthalpies of dissolution of metastable rock salt and thermodynamically stable wurtzite polymorphs of zinc oxide in aqueous H2SO4 have been measured in direct calorimetric experiments at 303 K and 0.1 MPa and the obtained results enabled determination of the standard enthalpy of the rock salt-to-wurtzite phase transition in ZnO, ΔtrH = -11.7+/-0.3 kJ/mol.
A new minimal model is constructed for the doped manganese oxides which exhibit colossal magnetoresistance (CMR), involving broad spin-majority conduction band as well as nearly localised spin-minority electron states. A simple mean field analysis yields a temperature-dependent hybridised band structure with suppressed carrier weight at the Fermi level. Spin stiffness is complex, indicating unusually strong spin wave damping. Experimental and theoretical investigations are needed to further verify the relevance of the proposed model.
We present results of an approach to incorporate redox-active manganese oxide into the 3-dimensional porous structure of carbon xerogels under self-limiting electroless conditions. By varying the structure of the carbon backbone, we found that deposition of manganese oxide preferably takes place on the external surface area of the carbon xerogels. From our detailed analysis we conclude that 3-dimensional carbon xerogels with particle and pore sizes ranging from 10 to 20 nm and low manganese oxide precursor concentration combined with long deposition times are beneficial for fast operating pseu…
Many positive electrode materials in lithium ion batteries include transition metals which are difficult to describe by electronic structure methods like density functional theory (DFT) due to the presence of multiple oxidation states. A prominent example is the lithium manganese oxide spinel Li$_x$Mn$_2$O$_4$ with $0\leq x\leq2$. While DFT, employing the local hybrid functional PBE0r, provides a reliable description, the need for extended computer simulations of large structural models remains a significant challenge. Here, we close this gap by constructing a DFT-based high-dimensional neural…
The lithium manganese oxide spinel Li$_x$Mn$_2$O$_4$, with $0\leq x\leq 2$, is an important example for cathode materials in lithium ion batteries. However, an accurate description of Li$_x$Mn$_2$O$_4$ by first-principles methods like density functional theory is far from trivial due to its complex electronic structure, with a variety of energetically close electronic and magnetic states. It was found that the local density approximation as well as the generalized gradient approximation (GGA) are unable to describe Li$_x$Mn$_2$O$_4$ correctly. Here, we report an extensive benchmark for differe…
We report a novel synthesis route of homogeneously manganese-doped titanium dioxide nanotubes in a broad concentration range. The scroll-type trititanate (H(2)Ti(3)O(7)) nanotubes prepared by hydrothermal synthesis were used as precursors. Mn2+ ions were introduced by an ion exchange method resulting Mn(x)H(2-x)Ti(3)O(7). In a subsequent heat-treatment they were transformed into Mn(y)Ti(1-y)O(2) where y=x/(3+x). The state and the local environment of the Mn2+ ions in the precursor and final products were studied by Electron Spin Resonance (ESR) technique. It was found that the Mn2+ ions occupy…
Layered LiMnO$_2$ and Li$_2$MnO$_3$ are of great interest for lithium-ion battery cathodes because of their high theoretical capacities. The practical application of these materials is, however, limited due to poor electrochemical performance. We herein report a comprehensive first-principles study of defect physics in LiMnO$_2$ and Li$_2$MnO$_3$ using hybrid-density functional calculations. We find that manganese antisites have low formation energies in LiMnO$_2$ and may act as nucleation sites for the formation of impurity phases. The antisites can also occur with high concentrations in Li$_…
A new mechanism is proposed to explain the colossal magnetoresistance and related phenomena. Moving electrons accompanied by Jahn-Teller phonon and spin-wave clouds may form composite polarons in ferromagnetic narrow-band manganites. The ground-state and finite-temperature properties of such composite polarons are studied in the present paper. By using a variational method, it is shown that the energy of the system at zero temperature decreases with the formation of composite polaron; the energy spectrum and effective mass of the composite polaron at finite temperature is found to be strongly …
Ruderman-Kittel-Kasuya-Yosida interaction even if their wave functions lack direct overlap. Theory predicts that spin-orbit scattering leads to a Dzyaloshinskii-Moriya type enhancement of this indirect exchange interaction, giving rise to chiral exchange terms. Here we present a combined spin-polarized scanning tunneling microscopy, angle-resolved photoemission, and density functional theory study of MnO$_2$ chains on Ir(100). Whereas we find antiferromagnetic Mn--Mn coupling along the chain, the inter-chain coupling across the non-magnetic Ir substrate turns out to be chiral with a $120^{\cir…
Rational combination holds the key for non-precious metal oxides and economic carbon materials to the creation of high performance air electrode materials. Carbon nanotubes (CNTs)-supported manganese oxides composite catalysts (CMnCs) were obtained by reacting commercial CNTs with MnO$_4^-$ in diluted H$_2$SO$_4$ with cancelling conventional hydrothermal processing or adding surfantant templates. CMnCs were then assembled into commercial air cathodes equipped in metal air fuel cells. CNTs demonstrated structurally much defective. Outer CNT walls were cracked into graphene nano pieces yet remai…
Field-induced magnetization jumps with similar characteristics are observed at low temperature for the intermetallic germanide Gd5Ge4and the mixed-valent manganite Pr0.6Ca0.4Mn0.96Ga0.04O3. We report that the field location -and even the existence- of these jumps depends critically on the magnetic field sweep rate used to record the data. It is proposed that, for both compounds, the martensitic character of their antiferromagnetic-to-ferromagnetic transitions is at the origin of the magnetization steps.
Manganese oxide-coated TiO2 nanotube array (NTA) was synthesized and applied for the (electro)catalytic oxidation of sulfide. By setting the electrodeposition parameters and calcination temperature, the coating obtained was MnO2 or Mn2O3, with rod or needle like morphology. Excellent catalytic activity of the Ti/TiO2 NTA/MnxOy anodes resulted in robust and selective oxidation of sulfide to elemental sulfur via an inner sphere complex between the sulfide ion and Mn-oxide. The penetration of the MnxOy inside the NTA improved adhesion and enhanced the electron transfer, thus enabling complete and…
Structural analysis of a layered manganese tungstate diaminoalkane hybrid series suggests that this compound forms a spin-5/2 spin-ladder structure. We use X-ray diffraction, electron microscopy and x-ray absorption spectroscopy results to infer the structure. DC magnetization of the manganese compound and a possible copper analogue appear to show that the manganese system behaves like 1-dimensional antiferromagnetic Heisenberg chains (i.e. $J_{\parallel} \gg J_{\perp})$ while the copper system is fitted well by a $S = {1/2}$ spin ladder model, giving the parameters $g = 1.920 \pm 0.008$, $J_{…
Polymorphs are common in nature and can be stabilized by applying external pressure in materials. The pressure/strain can also be induced by the gradually accumulated radiation disorder. However, in semiconductors, the radiation disorder accumulation typically results in the amorphization instead of engaging polymorphism. By studying these phenomena in gallium oxide we found that the amorphization may be prominently suppressed by the monoclinic to orthorhombic phase transition. Utilizing this discovery, a highly oriented single-phase orthorhombic film on the top of the monoclinic gallium oxide…
We point out that the existing experimental data of most manganese oxides show the {\sl frustrated} p-wave superconducting condensation in the ferromagnetic phase in the sense that the superconducting coherence is not long enough to cover the whole system. The superconducting state is similar to the $A_{1}$ state in superfluid He-3. The sharp drop of resistivity, the steep jump of specific heat, and the gap opening in tunneling are well understood in terms of the p-wave pairing. In addition, colossal magnetoresistance (CMR) is naturally explained by the superconducting fluctuations with increa…
Hybridization of semiconducting and magnetic materials into a single heterostructure is believed to be potentially applicable to the design of novel functional spintronic devices. In the present work we report epitaxial stabilization of four magnetically ordered iron oxide phases (Fe3O4, γ-Fe2O3, α-Fe2O3 and most exotic metastable ε-Fe2O3) in the form of nanometer sized single crystalline films on GaN(0001) surface. The epitaxial growth of as many as four distinctly different iron oxide phases is demonstrated within the same single-target Laser MBE technological process on a GaN semiconductor …
We describe the ground- and excited-state electronic structure of bulk MnO and NiO, two prototypical correlated electron materials, using coupled cluster theory with single and double excitations (CCSD). As a corollary, this work also reports the first implementation of unrestricted periodic ab initio equation-of motion CCSD. Starting from a Hartree-Fock reference, we find fundamental gaps of 3.46 eV and 4.83 eV for MnO and NiO respectively for the 16 unit supercell, slightly overestimated compared to experiment, although finite-size scaling suggests that the gap is more severely overestimated…
Mn is used as a dopant to improve the electromechanical properties of perovskite oxides. We elucidate the role of Mn defects and associated vacancies on the electronic, atomic and ferroelectric properties of BaTiO$_3$. Using density functional theory (DFT) and DFT+U we investigate the equilibrium geometry and electronic properties of Mn ion on A or B sites and with compensating oxygen vacancies. We study the change in the oxidation state of Mn in response to local environment changes, such as the presence of oxygen vacancies.
In the present work, the structural, magnetic, and electronic properties of the two- and one-dimensional honeycomb structures of recently synthesized MnO [Zhang et al. Nat. Commun., 20, 1073-1078 (2021)] are investigated by using first principles calculations. Our calculations show that the single layer 2D MnO crystal has a degenerate antiferromagnetic (AFM) ground state and a relatively less favorable ferromagnetic (FM) state. In addition, magnetic anisotropy calculations unveil that the easy-axis direction for magnetism originating from unpaired electron states in manganese atoms is normal t…
Lithium ion batteries often contain transition metal oxides like Li$_{x}$Mn$_2$O$_4$ ($0\leq x\leq2$). Depending on the Li content different ratios of Mn$^\text{III}$ to Mn$^\text{IV}$ ions are present. In combination with electron hopping the Jahn-Teller distortions of the Mn$^\text{III}$O$_6$ octahedra can give rise to complex phenomena like structural transitions and conductance. While for small model systems oxidation and spin states can be determined using density functional theory (DFT), the investigation of dynamical phenomena by DFT is too demanding. Previously, we have shown that a hi…
Under normal conditions, bulk crystals of BiScO$_3$ , BiCrO$_3$, BiMnO$_3$, BiFeO$_3$, and BiCoO$_3$ present three very different variations of the perovskite structure: an antipolar phase, a rhombohedral phase with a large polarization along the space diagonal of the pseudocubic unit cell, and a supertetragonal phase with even larger polarization. With the aim of understanding the causes for this variety, we have used a genetic algorithm to search for minima in the surface energy of these materials. Our results show that the number of these minima is very large when compared to that of typica…
In sharp contrast to molecular synthesis, materials synthesis is generally presumed to lack selectivity. The few known methods of designing selectivity in solid-state reactions have limited scope, such as topotactic reactions or strain stabilization. This contribution describes a general approach for searching large chemical spaces to identify selective reactions. This novel approach explains the ability of a nominally "innocent" Na$_2$CO$_3$ precursor to enable the metathesis synthesis of single-phase Y$_2$Mn$_2$O$_7$ -- an outcome that was previously only accomplished at extreme pressures an…
Gallium oxide with a corundum structure (α-Ga2O3) has recently attracted great attention in view of electronic and photonic applications due to its unique properties including a wide band gap exceeding that of the most stable beta phase (\b{eta}-Ga2O3). However, the lower thermal stability of the α-phase at ambient conditions in comparison with the \b{eta}-phase requires careful investigation of its resistance to other external influences such as ion irradiation, ion doping, etc. In this work, the structural changes under the action of Al+ ion irradiation have been investigated for a polymorph…
Quasiparticle calculations are performed to investigate the electronic band structures of various polymorphs of Hf and Zr oxides. The corrections with respect to density-functional-theory results are found to depend only weakly on the crystal structure. Based on these bulk calculations as well as those for bulk Si, the effect of quasiparticle corrections is also investigated for the band offsets at the interface between these oxides and Si assuming that the lineup of the potential at the interface is reproduced correctly within density-functional theory. On the one hand, the valence band offse…
Manganese oxides have received much attention over the years among the wide range of electrocatalysts for the oxygen evolution reaction (OER) due to their low toxicity, high abundance and rich redox chemistry. While many previous studies focused on the activity of these materials, a better understanding of the material transformations relating to activation or degradation is highly desirable, both from a scientific perspective and for applications. We electrodeposited Na-containing MnOx without long-range order from an alkaline solution to investigate these aspects by cyclic voltammetry, scann…
The data of different authors on the thermal conductivity of wustite Fe1-xO, magnetite F3O4, hematite Fe2O3 and pure iron are systematized. The generalized values are described by piecewise smooth functions containing as varying parameters the temperatures of magnetiv and polymorphic (for iron) transformations as well as the thermodynamic stability boundary (for wustite). At polymorphic transformation a finite break of the thermal conductivity function is envisaged, at othet critical points only a break of its temperature derivative is acceptable. The proposed formulas are presented in two for…
Zirconia (zirconium dioxide) and hafnia (hafnium dioxide) are binary oxides used in a range of applications. Because zirconium and hafnium are chemically equivalent, they have three similar polymorphs, and it is important to understand the properties and energetics of these polymorphs. However, while density functional theory calculations can get the correct energetic ordering, the energy differences between polymorphs depend very much on the specific density functional theory approach, as do other quantities such as lattice constants and bulk modulus. We have used highly accurate quantum Mont…
Transition-metal-oxide based resistance random access memory is a promising candidate for next-generation universal non-volatile memories. Searching and designing appropriate new materials used in the memories becomes an urgent task. Here, a new structure with the TaO2 formula was predicted using evolutionary algorithms in combination with first-principles calculations. This new structure having a triclinic symmetry (T-TaO2) is both energetically and dynamically more favorable than the commonly believed rutile structure (R-TaO2). Our hybrid functional calculations show that T-TaO2 is a semicon…
The relative energetic stability of the structural phases of common antiferromagnetic transition-metal oxides (MnO, FeO, CoO, and NiO) within the semilocal and hybrid density functionals are fraught with difficulties. In particular, MnO is known to be the most difficult case for almost all common semilocal and hybrid density approximations. Here, we show that the meta-generalized gradient approximation (meta-GGA) constructed from the cuspless hydrogen model and Pauli kinetic energy density (MGGAC) can lead to the correct ground state of MnO. The relative energy differences of zinc-blende (zb) …
An ab initio pseudopotential method based on density functional theory, generalized gradient corrections to exchange and correlation, and projector-augmented waves is used to investigate structural, energetical, electronic and optical properties of MgO, ZnO, and CdO in rocksalt, cesium chloride, zinc blende, and wurtzite structure. In the case of MgO we also examine the nickel arsenide structure and a graphitic phase. The stability of the ground-state phases rocksalt (MgO, CdO) and wurtzite (ZnO) against hydrostatic pressure and biaxial strain is studied. We also present the band structures of…
Corner-shared ABX$_3$ perovskites have long featured prominently in solid-state chemistry and condensed matter physics. Still, the joint understanding of their two main subgroups-halides and oxides-has not been fully developed. Indeed, unlike the case that compounds having a single repeated motif ("monomorphous"), certain cubic perovskites can manifest a non-thermal distribution of local motifs ("polymorphous networks"). Such intrinsic deformations can include positional degrees of freedom. Unlike thermal motion, such intrinsic distortions do not time-average to zero. The present study compare…
We use first-principles methods to study oxygen-octahedra rotations in ABO3 perovskite oxides. We focus on the short-period, perfectly antiphase or in-phase, tilt patterns that characterize most compounds and control their physical (e.g., conductive, magnetic) properties. Based on an analytical form of the relevant potential energy surface, we discuss the conditions for the stability of polymorphs presenting different tilt patterns, and obtain numerical results for a collection of thirty-five representative materials. Our results reveal the mechanisms responsible for the frequent occurrence of…
We investigate band gaps, equilibrium structures, and phase stabilities of several bulk polymorphs of wide-gap oxide semiconductors ZnO, TiO2,ZrO2, and WO3. We are particularly concerned with assessing the performance of hybrid functionals built with the fraction of Hartree-Fock exact exchange obtained from the computed electronic dielectric constant of the material. We provide comparison with more standard density-functional theory and GW methods. We finally analyze the chemical reduction of TiO2 into Ti2O3, involving a change in oxide stoichiometry. We show that the dielectric-dependent hybr…
Structural and magnetic properties have been studied for polycrystalline Zn_1-xMn_xO (x=0.02, 0.03, 0.05). Low-temperature (~500 oC) synthesis leaves unreacted starting ZnO and manganese oxides. Contrary to a recent report, no bulk ferromagnetism was observed for single-phase materials synthesized in air at temperatures above 900 oC. Single-phase samples show paramagnetic Curie-Weiss behavior.
Korea Institute of Ceramic Engineering & Technology（韩国陶瓷工程技术研究所）；Dong-Eui University（东义大学）；attocube systems AG（attocube系统股份公司）；Institute of Electronics, National Yang Ming Chiao Tung University（国立阳明交通大学电子研究所）；Silesian University of Technology（西里西亚理工大学）；Songshan Lake Materials Laboratory（松山湖材料实验室）；The Hong Kong Microelectronics Research and Development Institute（香港微电子技术研究与开发研究所）；Chinese Academy of Sciences（中国科学院）
Crystalline structures, zone-center phonon modes, and the related dielectric response of the three low-pressure phases of HfO2 have been investigated in density-functional theory using ultrasoft pseudopotentials and a plane-wave basis. The structures of low-pressure HfO2 polymorphs are carefully studied with both the local-density approximation (LDA) and the generalized gradient approximation (GGA). The fully relaxed structures obtained with either exchange-correlation scheme agree reasonably well with experiment, although LDA yields better overall agreement. After calculating the Born effecti…
Tantalum oxides (Ta$_2$O$_5$) are characterised by attractive physical and chemical properties, such as high dielectric constants and anti-reflection behaviour. Recently, Ta$_2$O$_5$ nanoparticles have also been proposed as possible enhancers of the relative biological effectiveness in hadrontherapy for cancer treatment. In principle, their electronic properties can be accurately investigated from first-principles simulations. However, the existence of several stable polymorphs of these oxides represents a major difficulty in order to calculate and disentangle their respective spectral feature…
We perform density functional theory plus dynamical mean field theory calculations to investi- gate internal charge transfer in an artificial superlattice composed of alternating layers of vanadate and manganite perovskite and Ruddlesden-Popper structure materials. We show that the elec- tronegativity difference between vanadium and manganese causes moderate charge transfer from VO2 to MnO2 layers in both perovskite and Ruddlesden-Popper based superlattices, leading to hole doping of the VO2 layer and electron doping of the MnO2 layer. Comparison of the perovskite and Ruddlesden-Popper based h…
