Magnetic neutron scattering measures spin-spin correlations giving information about the long-range spin order as well as the shape of the spin density in magnetic materials. Similarly, detailed first principles calculations directly compute the spin density in materials. In this work, the authors carefully compare experimentally measured magnetic neutron intensities to three levels of theory: density functional theory in two approximations, and fixed-node diffusion Monte Carlo. While each theory performs similarly for the simple antiferromagnet MnO, there are significant differences between density functional theory and diffusion Monte Carlo in NiO. For both materials, fixed-node diffusion Monte Carlo shows the lowest RMS error with respect to experiment for the form factor and the intensity. Through connection of the intensities and form factors to the real-space spin densities, it is shown that diffusion Monte Carlo spin density becomes more diffuse by spreading spin away from the bond directions. This benchmark is of importance when considering the efficacy of an ab initio calculation in capturing both the long-range magnetic correlations and the microscopic spin details of magnetic systems.
We report calculations of the band structures and density of states of the four transition metal monoxides MnO, FeO, CoO and NiO using the hybrid density functional sX-LDA. Late transition metal oxides are prototypical examples of strongly correlated materials, which pose challenges for electronic structure methods. We compare our results with available experimental data and show that our calculations yield accurate predictions for the fundamental band gaps and valence bands of FeO, CoO and NiO. For MnO, the band gaps are underestimated, suggesting additional many-body effects that are not cap…
We present spin wave dispersions in MnO, NiO, and $α$-MnAs based on the quasiparticle self-consistent $GW$ method (\qsgw), which determines an optimum quasiparticle picture. For MnO and NiO, \qsgw results are in rather good agreement with experiments, in contrast to the LDA and LDA+U description. For $α$-MnAs, we find a collinear ferromagnetic ground state in \qsgw, while this phase is unstable in the LDA.
A band structure description of the observed large band gaps and moments in both the antiferromagnetic (AFM) and paramagnetic (PM) phases of the classic NaCl-structure Mott insulators MnO, FeO, CoO, and NiO is provided by ordinary, single-determinant density functional theory method. As noted by previous authors, the ordered AFM phases already show in band theory significant band gaps. However, for the disordered PM phases the commonly used band model has been to assume the macroscopically observed, averaged NaCl structure, where all transition metal sites are forced to be symmetry-equivalent …
The accurate ab-initio simulation of periodic solids with strong correlations is one of the grand challenges of condensed matter. While mature methods exist for weakly correlated solids, the ab-initio description of strongly correlated systems is an active field of research. In this work, we show results for the single particle spectral function of the two correlated $d$-electron solids NiO and MnO from self-energy embedding theory. Unlike earlier work, the theory does not use any adjustable parameters and is fully ab-initio, while being able to treat both the strong correlation and the non-lo…
Recently, two nonempirical hybrid functionals, dielectric-dependent range-separated hybrid functional based on the Coulomb-attenuating method (DD-RSH-CAM) and doubly screened hybrid functional (DSH), have been suggested by [Chen et al, Phys. Rev. Mater. 2, 073803 (2018)] and [Cui et al, J. Phys. Chem. Lett. 9, 2338 (2018)], respectively. These two hybrid functionals are both based on a common model dielectric function approach, but differ in the way how to non-empirically obtain the range-separation parameter. By retaining the full short-range Fock exchange and a fraction of the long-range Foc…
X-ray diffraction with synchrotron radiation has been used for the first time to study chemical interaction in the MnO-ZnO system at 4.8 GPa and temperatures up to 1600 K. Above 750 K, the chemical reaction between MnO and ZnO has been observed that resulted in the formation of rock salt (rs) Mn1-xZnxO solid solutions (0.3 \leq x \leq 0.7). The lattice parameters of these solid solutions have been in situ measured at high pressure as a function of temperature, and corresponding thermal expansion coefficients have been calculated.
Comparative study of magnetic exchange parameters and magnon dispersions in NiO and MnO from first principles
Paul Scherrer Institute（保罗谢勒研究所）；National Centre for Computational Design and Discovery of Novel Materials (MARVEL)（新型材料计算设计与发现国家中心（MARVEL））；Centro Brasileiro de Pesquisas Físicas (CBPF)（巴西物理研究中心（CBPF））；University of California Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）；Dipartimento di Fisica dell’Universitá di Pisa（比萨大学物理系）；Istituto Italiano di Tecnologia（意大利理工大学）；Stanford University（斯坦福大学）；SLAC National Accelerator Laboratory（SLAC国家加速器实验室）
High real-space-resolution atomic pair distribution functions of La_(1-x)Ca_(x)MnO_3 (x=0.12, 0.25 and 0.33) have been measured using high-energy x-ray powder diffraction to study the size and shape of the MnO_6 octahedron as a function of temperature and doping. In the paramagnetic insulating phase we find evidence for three distinct bond-lengths (~ 1.88, 1.95 and 2.15A) which we ascribe to Mn^{4+}-O, Mn^{3+}-O short and Mn^{3+}-O long bonds respectively. In the ferromagnetic metallic (FM) phase, for x=0.33 and T=20K, we find a single Mn-O bond-length; however, as the metal-insulator transiti…
X-ray diffraction experiments were performed on MnO confined in mesoporous silica SBA-15 and MCM-41 matrices with different channel diameters. The measured patterns were analyzed by profile analysis and compared to numerical simulations of the diffraction from confined nanoparticles. From the lineshape and the specific shift of the diffraction reflections it was shown that the embedded objects form ribbon-like structures in the SBA-15 matrices with channels diameters of 47-87 Å, and nanowire-like structures in the MCM-41 matrices with channels diameters of 24-35 Å. In the latter case the confi…
We report a method for acquiring Foucault images and small-angle electron diffraction patterns in external magnetic fields using a conventional transmission electron microscope without any modification. In the electron optical system that we have constructed, external magnetic fields parallel to the optical axis can be controlled using the objective lens pole piece under weak excitation conditions in the Foucault mode and the diffraction mode. We observe two ferromagnetic perovskite-type manganese oxides, La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ and Nd$_{0.5}$Sr$_{0.5}$MnO$_{3}$, in order to visualize ma…
Neutron diffraction has been used to investigate antiferromagnetism since 1949. Here we show that antiferromagnetic reflections can also be seen in transmission electron diffraction patterns from NiO. The diffraction patterns taken here came from regions as small as 10.5 nm and such patterns could be used to form an image of the antiferromagnetic structure with a nanometre resolution.
Here we systematically explore the use of pulsed laser deposition technique (PLD) to grow three basic oxides that have rocksalt structure but different chemical stability in the ambient atmosphere: NiO (stable), MnO (metastable) and EuO (unstable). By tuning laser fluence, an epitaxial single-phase nickel oxide thin-film growth can be achieved in a wide range of temperatures from 10 to 750 °C. At the lowest growth temperature, the out-of-plane strain raises to 1.5%, which is five times bigger than that in a NiO film grown at 750 °C. MnO thin films that had long-range ordered were successfully …
Polycrystalline samples of the quarter-doped manganites $R_{0.75}$Ca$_{0.25}$MnO$_3$ ($R$ = Y, Tb, Dy, Ho, and Er) were studied by X-ray diffraction and AC/DC susceptibility measurements. All five samples are orthorhombic and exhibit similar magnetic properties: enhanced ferromagnetism below $T_1$ ($\sim80$ K) and a spin glass (SG) state below $T_{SG}$ ($\sim30$ K). With increasing $R^{3+}$ ionic size, both $T_1$ and $T_{SG}$ generally increase. The single crystal neutron diffraction results on Tb$_{0.75}$Ca$_{0.25}$MnO$_3$ revealed that the SG state is mainly composed of a short-range ordered…
We report investigation of structural phase transitions in technologically important material sodium niobate as a function of temperature on heating over 300-1075 K. Our high resolution powder neutron diffraction data show variety of structural phase transitions ranging from non-polar antiferrodistortive to ferroelectric and antiferroelectric in nature. Discontinuous jump in lattice parameters is found only at 633 K that indicates that the transition of orthorhombic antiferroelectric P (space group Pbcm) to R (space group Pbnm) phase is first order in nature, while other successive phase trans…
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…
Using fully self-consistent thermal broken-symmetry GW we construct effective magnetic Heisenberg Hamiltonians for a series of transition metal oxides (NiO, CoO, FeO, MnO), capturing a rigorous but condensed description of the magnetic states. Then applying high-temperature expansion, we find the decomposition coefficients for spin susceptibility and specific heat. The radius of convergence of the found series determine the Neel temperature. The NiO, CoO, and FeO contain a small ferromagnetic interaction between the nearest neighbors (NN) and the dominant antiferromagnetic interaction between …
The crystal and magnetic structure of La_{1-x}Sr_{1+x}MnO_4 (0<x<0.7) has been studied by diffraction techniques and high resolution capacitance dilatometry. There is no evidence for a structural phase transition like those found in isostructural cuprates or nickelates, but there are significant structural changes induced by the variation of temperature and doping which we attribute to a rearrangement of the orbital occupation.
We have carried out systematic temperature-dependent neutron diffraction measurements in conjunction with dielectric spectroscopy from 6 to 300 K for sodium niobate based compounds (1-x) NaNbO3 -xBaTiO3 (NNBTx). The dielectric constant is measured both as a function of temperature and frequency. It shows an anomaly at different temperatures in cooling and heating cycles and exhibits a large thermal hysteresis of 150 K for the composition x=0.03. The dielectric constant is found to be dispersive in nature and suggests a relaxor ferroelectric behavior. In order to explore structural changes as a…
La$_{0.7}$Sr$_{0.3}$MnO$_3$ polycrystalline samples have been prepared using different synthesis routes. X-ray Diffraction (XRD) confirms that the samples are of single phase with R$\bar{3}$c space group. The surface morphology and particle size has been measured using Field Emission Scanning Electron Microscopy (FESEM). Magnetic measurement shows that the magnetization in the materials are affected by low crystallite size which destroys the spin ordering due to strain at grain boundaries and in turn also lead to reduction in magnetization as well as an enhanced coercivity in the material.
Zero field cooled (ZFC)/Field Cooled (FC) magnetization curves of a bulk MnO single crystal show a peculiar peak at low temperatures (~40K) similar to the low temperature peak observed in MnO nanoparticles. In order to investigate the origin of this peak, the spin structure of a MnO single crystal has been studied and compared with a single phase powder sample using magnetometry and polarized neutron scattering. Both magnetometry and polarized neutron diffraction results confirm the antiferromagnetic (AF) phase transition at the Néel temperature T_N of 118K, in both powder and single crystal f…
The crystal and magnetic structure of polycrystalline $La{}_{0.5-x}Nd{}_{x}Ca_{0.5}MnO{}_{3}$ (0.0 \ensuremath{\le} x \ensuremath{\le} 0.5) samples have been investigated using magnetization, resistivity, transmission electron microscope, and neutron diffraction techniques. The samples are isostructural and possess orthorhombic structure in \textit{Pnma} space group. On lowering of temperature, the samples exhibit CE - type antiferromagnetic structure coexisting with a weak ferromagnetic ordering. The charge and orbitally ordered antiferromagnetic phase is weakened by the growth of ferromagnet…
Rare-earth niobates and tantalates possess low thermal conductivities, which can be further reduced in high-entropy compositions. Here, a large number of 40 compositions are synthesized to investigate the origin of low thermal conductivity. Amongst, 29 possess single (nominally cubic) fluorite phases and most of them are new compositionally complex (medium- or high-entropy) compositions. One new finding is that doping 2 % of light element cations can further reduce thermal conductivity. This large data set enables the discovery of a negative correlation between the thermal conductivity and ave…
We present a comparative study on the morphology and structural as well as magnetic properties of crystalline Fe$_3$O$_4$/NiO bilayers grown on both MgO(001) and SrTiO$_3$(001) substrates by reactive molecular beam epitaxy. These structures are investigated by means of x-ray photoelectron spectroscopy, low energy electron diffraction, x-ray reflectivity and diffraction as well as vibrating sample magnetometry. While the lattice mismatch of NiO grown on MgO(001) is only 0.8%, it is exposed to a lateral lattice mismatch of -6.9% if grown on SrTiO$_3$. In the case of Fe$_3$O$_4$, the misfit strai…
An experimental determination of the magnetic pair distribution function (mPDF) defined in an earlier paper (Frandsen, Yang, and Billinge. (2014) Acta Crystallogr. A, 70(1), 3-11) is presented for the first time. The mPDF was determined from neutron powder diffraction data from a reactor and a neutron time-of-flight total scattering source on a powder sample of the antiferromagnetic oxide MnO. A description of the data treatment that allowed the measured mPDF to be extracted and then modelled is provided and utilized to investigate the low-temperature structure of MnO. Atomic and magnetic co-r…
Contradictory reports about the electronic and magnetic behavior of bulk Nd0:5Ba0:5MnO3 with uniform disorder exist in the literature. In this work, we investigate the thin films of Nd0:5Ba0:5MnO3, grown by pulsed laser deposition. The success of epitaxial growth in a layer-by-layer mode and high quality of the films have been confirmed by in-situ reflection high energy electron diffraction, atomic force microscopy, X-ray reflectivity, and, X-ray diffraction. These films are found to be insulting and exhibit spin-glass behavior at low temperatures. The study offers an opportunity to tune the c…
Nd_0.5 Ca_0.5 MnO_3 (NCMO) nanoparticles (average diameter ~ 20 and 40 nm) are synthesized by polymeric precursor sol-gel method and characterized by X- ray diffraction, transmission electron microscopy (TEM), selective area electron diffraction (SAED), superconducting quantum interference device (SQUID) magnetometery and resistivity measurements. Both single crystalline and polycrystalline particles are present in the samples and they are found to retain the orthorhombic structure of the bulk NCMO. However, most strikingly, in the 20 nm particles, the charge ordered (CO) and the antiferromagn…
We have studied the phase diagram of La$_{1-x}$Ca$_{x}$MnO$_{3}$ for $0.5\leq x\leq 0.9$ using neutron powder diffraction and magnetization measurements. At 300 K all samples are paramagnetic and single phase with crystallographic symmetry $Pnma$. As the temperature is reduced a structural transition is observed which is to a charge-ordered state only for certain x. On further cooling the material passes to an antiferromagnetic ground state with Neel temperature $T_N$ that depends on x. For $0.8\leq x\leq 0.9$ the structural transformation occurs at the same temperature as the magnetic transit…
Bilayers of the oxide 3d ferromagnet La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) and the 5d paramagnet SrIrO$_{3}$ (SIO) with large spin-orbit coupling (SOC) have been investigated regarding the impact of interfacial SOC on magnetic order. For the growth sequence of LSMO on SIO, ferromagnetism is strongly altered and large out-of-plane-canted anisotropy associated with lacking magnetic saturation up to 4 T has been observed. Thin bilayer films have been grown coherently in both growth sequences on SrTiO$_3$ (001) by pulsed laser deposition and structurally characterized by scanning transmission elect…
High resolution neutron diffraction shows that the mesoscopic separation into ferromagnetic (FM) and antiferromagnetic (AFM) phases and the FM transition temperature T_C in the perovskite manganite (La_{1-y}Pr_{y})_{0.7}Ca_{0.3}MnO_3 strongly depend on the quenched correlated disorder. The different disorder strengths are achieved by different procedures of the sample synthesis and quantitatively characterized by the micro-strain-type diffraction peak broadening. The system shifts to predominantly one phase state with smaller T_C as the correlated disorder strength is decreased supporting the …
Results of structural neutron diffraction study, magnetization and ESR measure-ments are presented for insulating Nd0.75Ba0.25MnO3, Tc = 129 K. The crystal structure is refined in the range 4.2-300 K. The compound is found to exhibit the Jahn-Teller (JT) transition at 250 K. The field cooled (FC) magnetization data are in a reasonable agreement with the predictions for a 3D isotropic ferromagnet above Tc. However, these measurements reveal a difference between the FC and zero FC data in the paramagnetic region. ESR results are also in a correspondence with behavior of a cubic ferromagnet above…
The local epitaxial growth of pulsed laser deposited Ca$_2$MnO$_4$ films on polycrystalline spark plasma sintered Sr$_2$TiO$_4$ substrates was investigated to determine phase formation and preferred epitaxial orientation relationships ($ORs$) for isostructural Ruddlesden-Popper (RP) heteroepitaxy, further developing the high-throughput synthetic approach called Combinatorial Substrate Epitaxy (CSE). Both grazing incidence X-ray diffraction and electron backscatter diffraction (EBSD) patterns of the film and substrate were indexable as single-phase RP-structured compounds. The optimal growth te…
We use femtosecond electron diffraction to study ultrafast lattice dynamics in the highly correlated antiferromagnetic (AF) semiconductor NiO. Using the scattering vector (Q) dependence of Bragg diffraction, we introduce a Q-resolved effective lattice temperature, and identify a nonthermal lattice state with preferential displacement of O compared to Ni ions, which occurs within ~0.3 ps and persists for 25 ps. We associate this with transient changes to the AF exchange striction-induced lattice distortion, supported by the observation of a transient Q-asymmetry of Friedel pairs. Our observatio…
We investigate the structural and magnetic properties of La$_{0.7}$Sr$_{0.3}$CrO$_3$ (LSCO)/La$_{0.7}$Sr$_{0.3}$MnO$_3$(LSMO) heterostructures grown on (001)-oriented MgO by molecular beam epitaxy. Due to the large film-substrate lattice mismatch, strain relaxation is found to occur within the first 2-3 unit cells (uc) of the film as evidenced by reflection high energy electron diffraction and high-resolution synchrotron X-ray reciprocal space mapping. We find that the presence of the LSCO spacer and capping layers leads to ferromagnetism in ultra-thin LSMO layers with thicknesses on the order…
In this research, we report on the synthesis and characterization of $La_{0.67}Ca_{0.33}MnO_3$ (LCMO), $La_{0.67}Ba_{0.33}MnO_3$ (LBMO), and $La_{0.67}Sr_{0.33}MnO_3$ (LSMO) perovskites. Precursor powders for the perovskite samples were prepared using ball mailing technique. The resulting powder was pressed into disks which were subsequently sintered at 1000 C for 2h. The structural characteristics of the prepared samples were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM), and the magnetic properties were investigated using vibrating sample magnetometry (VSM…
$La_{0.7}Ca_{0.3}MnO_3$ samples were prepared in nano- and polycrystalline forms by sol-gel and solid state reaction methods, respectively, and structurally characterized by synchrotron X-ray diffraction. The magnetic properties determined by ac susceptibility and dc magnetization measurements are discussed. The magnetocaloric effect in this nanocrystalline manganite is spread over a broader temperature interval than in the polycrystalline case. The relative cooling power of the poly- and nanocrystalline manganites is used to evaluate a possible application for magnetic cooling below room temp…
Investigating the Electromechanical Behavior of Unconventionally Ferroelectric $Hf_{0.5}Zr_{0.5}O_{2}$-based Capacitors Through Operando Nanobeam X-ray Diffraction
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) …
(111)NiO epitaxial layers are grown on c-sapphire substrates by pulsed laser deposition (PLD) technique. Structural and morphological properties of the films are studied using in-plane as well as out-of-plane high resolution X-ray diffraction and atomic force microscopy techniques as functions of growth temperature, oxygen pressure and the pulses count of the laser. The study shows that continuous epitaxial films of thickness as low as 3 nm with high crystalline quality, smooth surface and interface morphology can be grown by this technique. The study also reveals the co-existence of 60°-rotat…
Magnetism of transition metal (TM) oxides is usually described in terms of the Heisenberg model, with orientation-independent interactions between the spins. However, the applicability of such a model is not fully justified for TM oxides because spin polarization of oxygen is usually ignored. In the conventional model based on the Anderson principle, oxygen effects are considered as a property of the TM ion and only TM interactions are relevant. Here, we perform a systematic comparison between two approaches for spin polarization on oxygen in typical TM oxides. To this end, we calculate the ex…
Tetragonally distorted \(\rm{Mn}_{3-x}\rm{Ga}_x\) thin films with \(0.1< x < 2\) show a strong perpendicular magnetic anisotropy and low magnetization and thus have the potential to serve as electrodes in spin transfer torque magnetic random access memory. Because a direct capping of these films with MgO is problematic due to oxide formation, we examined the influence of a CoFeB interlayer, and of two different deposition methods for the MgO barrier on the formation of interfacial MnO for \(\rm{Mn}_{62}\rm{Ga}_{38}\) by element specific X-ray absorption spectroscopy (XAS) and magnetic circular…
We have carried out high magnetic field studies of single-crystalline Li$_2$MnO$_3$, a honeycomb lattice antiferromagnet. Its magnetic phase diagram was mapped out using magnetization measurements at applied fields up to 35 T. Our results show that it undergoes two successive meta-magnetic transitions around 9 T fields applied perpendicular to the ab-plane (along the c*-axis). These phase transitions are completely absent in the magnetization measured with field applied along the ab-plane. In order to understand this magnetic phase diagram, we developed a mean-field model starting from the cor…
The Lead-iron-niobate, (PbFe0.5Nb0.5O3 or PFN) was synthesized by low temperature sintering Single Step / Solid State Reaction Method. The 700 C / 2 hrs calcined powder was sintered at 1050 C / 1 hr. The sintered pellets were characterized through X-Ray Diffraction and Neutron Diffraction at room temperature. It is found from the XRD pattern that the materials is in single phase with no traces of pyrochlore phase. It was also confirmed from the neutron diffraction pattern, the structure of PFN to be monoclinic, belongs to space group C m. Structural studies has been carried out by refining the…
Nanoparticles (dia ~ 5 - 7 nm) of Bi_0.5 X_0.5(X=Ca,Sr)MnO_3 are prepared by polymer assisted sol-gel method and characterized by various physico-chemical techniques. X-ray diffraction gives evidence for single phasic nature of the materials as well as their structures. Mono dispersed to a large extent, isolated nanoparticles are seen in the transmission electron micrographs. High resolution electron microscopy shows the crystalline nature of the nanoparticles. Superconducting quantum interferometer based magnetic measurements from 10 K to 300 K show that these nanomanganites retain the charge…
First principles density functional theory DFT+U calculations and experimental neutron diffraction structure analyses were used to determine the low-temperature crystallographic and magnetic structure of bixbyite Mn2O3. The energies of various magnetic arrangements, calculated from first principles, were fit to a cluster-expansion model using a Bayesian method that overcomes a problem of underfitting caused by the limited number of input magnetic configurations. The model was used to predict the lowest-energy magnetic states. Experimental determination of magnetic structure benefited from opti…
Interface magnetic coupling and magnetization dynamic of La$_{2/3}$Sr$_{1/3}$MnO$_3$ single layer and (La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$)$_n$ (n = 1, 5) superlattice on SrTiO$_3$(001) substrate
Single Crystals of Nd$_{1-x}$Ca$_{1+x}$MnO$_{4}$ have been prepared by the traveling floating-zone method, and possible evidence of a charge -orbital density wave in this material presented earlier [PRB68,092405 (2003)] using High Resolution Electron Microscopy [HRTEM] and Electron Diffraction [ED]. In the current note we present direct evidence of charge-orbital ordering in this material using heat capacity measurements. Our heat capacity measurements indicate a clear transition consistent with prior observation. We find two main transitions, one at temperature $T_{_H}^{HC}=310-314$ K, and ot…
Hole doping in Nd${}_{2}$NiO${}_{4.00}$ can be either achieved by substituting the trivalent Nd atoms by bivalent alkaline earth metals or by oxygen doping, yielding Nd${}_{2}$NiO${}_{4+δ}$. In this study, we investigated the interplay between oxygen and spin ordering for a low oxygen doping concentration i.e. Nd${}_{2}$NiO${}_{4.10}$. Although the extra oxygen doping level remains rather modest with only one out of 20 possible interstitial tetrahedral lattice sites occupied, we observed by single crystal neutron diffraction the presence of a complex 3D modulated structure related to oxygen or…
FeXMn1-XS (0 <x< 0.3) synthesized on the basis of α-MnS are the novel Mott-type substances with the rock salt structure. Neutron diffraction study shows that the shift of the Neel temperature of these materials from 150 (x = 0) to 200 K (x = 0.29) under the action of chemical pressure (x) is accompanied by a decrease in the cubic NaCl lattice parameters. The structural transition with a change in crystal symmetry and a decrease in resistance before the magnetic transition at x = 0.25 is found. Therefore, FeXMn1-XS are interesting materials for both fundamental study of the interrelation betwee…
