Browse
Submit Data
Databases
API
Help

Dataset Information

14 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Cation, magnetic, and charge ordering in MnFe₃O₅.

ABSTRACT: The recently-discovered high pressure material MnFe₃O₅ displays a rich variety of magnetically ordered states on cooling. Fe spins order antiferromagnetically below a Néel transition at 350 K. A second transition at 150 K marks Mn spin order that leads to spin canting of some of the Fe spins and ferrimagnetism. A further transition at 60 K is driven by charge ordering of Fe²⁺ and Fe³⁺ over two inequivalent Fe sites, with further canting of all spins. Electrical resistivity measurements reveal semiconducting behaviour in MnFe₃O₅ with a change in activation energy at 285 K.

SUBMITTER: Hong KH

PROVIDER: S-EPMC6003543 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Cation, magnetic, and charge ordering in MnFe3O5.

Hong K H KH Arevalo-Lopez A M AM Coduri M M McNally G M GM Attfield J P JP

Journal of materials chemistry. C 20180116 13

The recently-discovered high pressure material MnFe3O5 displays a rich variety of magnetically ordered states on cooling. Fe spins order antiferromagnetically below a Néel transition at 350 K. A second transition at 150 K marks Mn spin order that leads to spin canting of some of the Fe spins and ferrimagnetism. A further transition at 60 K is driven by charge ordering of Fe2+ and Fe3+ over two inequivalent Fe sites, with further canting of all spins. E ...[more]

PMID: 30009028

Similar Datasets

Co-doped MnFe2O4 nanoparticles: magnetic anisotropy and interparticle interactions.

Project description:The effect of cobalt doping on the magnetic properties of Mn1- x Co x Fe2O4 nanoparticles was investigated. All samples consist of ensembles of nanoparticles with a spherical shape and average diameter of about 10 nm, showing small structural changes due to the substitution. Besides having the same morpho-structural properties, the effect of the chemical composition, i.e., the amount of Co doping, produces marked differences on the magnetic properties, especially on the magnetic anisotropy, with evident large changes in the coercive field. Moreover, Co substitution has a profound effect on the interparticle interactions, too. A dipolar-based interaction regime is detected for all samples; in addition, the intensity of the interactions shows a possible relation with the single particle anisotropy. Finally, the sample with the strongest interaction regime shows a superspin glass state confirmed by memory effect dynamics.

| S-EPMC6466680 | biostudies-literature

Magnetic-charge ordering and phase transitions in monopole-conserved square spin ice.

Project description:Magnetic-charge ordering and corresponding magnetic/monopole phase transitions in spin ices are the emergent topics of condensed matter physics. In this work, we investigate a series of magnetic-charge (monopole) phase transitions in artificial square spin ice model using the conserved monopole density algorithm. It is revealed that the dynamics of low monopole density lattices is controlled by the effective Coulomb interaction and the Dirac string tension, leading to the monopole dimerization which is quite different from the dynamics of three-dimensional pyrochlore spin ice. The condensation of the monopole dimers into monopole crystals with staggered magnetic-charge order can be predicted clearly. For the high monopole density cases, the lattice undergoes two consecutive phase transitions from high-temperature paramagnetic/charge-disordered phase into staggered charge-ordered phase before eventually toward the long-range magnetically-ordered phase as the ground state which is of staggered charge order too. A phase diagram over the whole temperature-monopole density space, which exhibits a series of emergent spin and monopole ordered states, is presented.

| S-EPMC4625371 | biostudies-literature

Ultrafast charge ordering by self-amplified exciton-phonon dynamics in TiSe2.

Project description:The origin of charge density waves (CDWs) in TiSe[Formula: see text] has long been debated, mainly due to the difficulties in identifying the timescales of the excitonic pairing and electron-phonon coupling (EPC). Without a time-resolved and microscopic mechanism, one has to assume simultaneous appearance of CDW and periodic lattice distortions (PLD). Here, we accomplish a complete separation of ultrafast exciton and PLD dynamics and unravel their interplay in our real-time time-dependent density functional theory simulations. We find that laser pulses knock off the exciton order and induce a homogeneous bonding-antibonding transition in the initial 20 fs, then the weakened electronic order triggers ionic movements antiparallel to the original PLD. The EPC comes into play after the initial 20 fs, and the two processes mutually amplify each other leading to a complete inversion of CDW ordering. The self-amplified dynamics reproduces the evolution of band structures in agreement with photoemission experiments. Hence we resolve the key processes in the initial dynamics of CDWs that help elucidate the underlying mechanism.

| S-EPMC6940384 | biostudies-literature

Observation of novel charge ordering and spin reorientation in perovskite oxide PbFeO3.

Project description:PbMO3 (M = 3d transition metals) family shows systematic variations in charge distribution and intriguing physical properties due to its delicate energy balance between Pb 6s and transition metal 3d orbitals. However, the detailed structure and physical properties of PbFeO3 remain unclear. Herein, we reveal that PbFeO3 crystallizes into an unusual 2ap × 6ap × 2ap orthorhombic perovskite super unit cell with space group Cmcm. The distinctive crystal construction and valence distribution of Pb2+0.5Pb4+0.5FeO3 lead to a long range charge ordering of the -A-B-B- type of the layers with two different oxidation states of Pb (Pb2+ and Pb4+) in them. A weak ferromagnetic transition with canted antiferromagnetic spins along the a-axis is found to occur at 600 K. In addition, decreasing the temperature causes a spin reorientation transition towards a collinear antiferromagnetic structure with spin moments along the b-axis near 418 K. Our theoretical investigations reveal that the peculiar charge ordering of Pb generates two Fe3+ magnetic sublattices with competing anisotropic energies, giving rise to the spin reorientation at such a high critical temperature.

| S-EPMC7997894 | biostudies-literature

Carboxylated PEG-Functionalized MnFe2O4 Nanocubes Synthesized in a Mixed Solvent: Morphology, Magnetic Properties, and Biomedical Applications.

Project description:Ferrites are one of the most studied materials around the globe due to their distinctive biological and magnetic properties. In the same line, anisotropic MnFe2O4 nanoparticles have been explored as a potential candidate possessing excellent magnetic properties, biocompatibility, and strong magnetic resonance imaging (MRI) properties such as r2 relaxivity for magnetic field-guided biomedical applications. The current work reports the synthesis and morphological evolution of MnFe2O4 nanocubes (MNCs) in a hydrothermal process using different volume ratios of water and ethanol. The synthesis protocol was designed to influence the properties of the ferrite nanocubes, for example, the variation in surface tension, dielectric properties, and the ionic character of the solvent, and this has been achieved by adding ethanol into water during the synthesis. Pristine MnFe2O4 is formed with well-defined cubic to irregular cubic shapes with the addition of ethanol, as evidenced from XRD, field emission scanning electron microscopy, and porosity measurements. MNCs have been investigated for magnetic hyperthermia and MRI applications. Well-defined cubic-shaped MNCs with uniform size distribution possessed a high saturation magnetization of 63 emu g-1 and a transverse relaxivity (r2) of 216 mM-1 s-1 (Mn + Fe). Furthermore, the colloidal nanocubes showed concentration-dependent hyperthermic response under an alternating magnetic field. The MNCs are biocompatible but advantageously show anticancer activities on breast cancer MCF 7 and MDA-MB-231 cells.

| S-EPMC7931194 | biostudies-literature

Suppression of magnetic ordering in XXZ-type antiferromagnetic monolayer NiPS3.

Project description:How a certain ground state of complex physical systems emerges, especially in two-dimensional materials, is a fundamental question in condensed-matter physics. A particularly interesting case is systems belonging to the class of XY Hamiltonian where the magnetic order parameter of conventional nature is unstable in two-dimensional materials leading to a Berezinskii-Kosterlitz-Thouless transition. Here, we report how the XXZ-type antiferromagnetic order of a magnetic van der Waals material, NiPS3, behaves upon reducing the thickness and ultimately becomes unstable in the monolayer limit. Our experimental data are consistent with the findings based on renormalization-group theory that at low temperatures a two-dimensional XXZ system behaves like a two-dimensional XY one, which cannot have a long-range order at finite temperatures. This work provides the experimental examination of the XY magnetism in the atomically thin limit and opens opportunities of exploiting these fundamental theorems of magnetism using magnetic van der Waals materials.

| S-EPMC6341093 | biostudies-literature

Single phase charge ordered stoichiometric CaFe3O5 with commensurate and incommensurate trimeron ordering.

Project description:Mixed-valent transition metal compounds display complex structural, electronic and magnetic properties which can often be exquisitely tuned. Here the charge-ordered state of stoichiometric CaFe3O5 is probed using neutron powder diffraction, Monte Carlo simulation and symmetry analysis. Magnetic ordering is dominated by the formation of ferromagnetic Fe3+-Fe2+-Fe3+ trimers which are evident above the magnetic ordering transition. Between TN = 289 K and 281 K an incommensurate magnetically ordered phase develops due to magnetic frustration, but a spin Jahn-Teller distortion lifts the frustration and enables the magnetic ordering to lock in to a charge-ordered commensurate state at lower temperatures. Stoichiometric CaFe3O5 exhibits single phase behaviour throughout and avoids the phase separation into two distinct crystallographic phases with different magnetic structures and Fe valence distributions reported recently, which likely occurs due to partial Fe2+ for Ca2+ substitution. This underlines the sensitivity of the magnetism and chemistry of these mixed-valent systems to composition.

| S-EPMC6889228 | biostudies-literature

Probing the interplay between quantum charge fluctuations and magnetic ordering in LuFe2O4.

Project description:The mechanisms producing strong coupling between electric and magnetic order in multiferroics are not always well understood, since their microscopic origins can be quite different. Hence, gaining a deeper understanding of magnetoelectric coupling in these materials is the key to their rational design. Here, we use ultrafast optical spectroscopy to show that the influence of magnetic ordering on quantum charge fluctuations via the double-exchange mechanism can govern the interplay between electric polarization and magnetism in the charge-ordered multiferroic LuFe2O4.

| S-EPMC3772380 | biostudies-other

Cation Distributions and Magnetic Properties of Ferrispinel MgFeMnO4.

Project description:The crystal structure and magnetic properties of the cubic spinel MgFeMnO4 were studied by using a series of in-house techniques along with large-scale neutron diffraction and muon spin rotation spectroscopy in the temperature range between 1.5 and 500 K. The detailed crystal structure is successfully refined by using a cubic spinel structure described by the space group Fd3̅m. Cations within tetrahedral A and octahedral B sites of the spinel were found to be in a disordered state. The extracted fractional site occupancies confirm the presence of antisite defects, which are of importance for the electrochemical performance of MgFeMnO4 and related battery materials. Neutron diffraction and muon spin spectroscopy reveal a ferrimagnetic order below TC = 394.2 K, having a collinear spin arrangement with antiparallel spins at the A and B sites, respectively. Our findings provide new and improved understanding of the fundamental properties of the ferrispinel materials and of their potential applications within future spintronics and battery devices.

| S-EPMC7759007 | biostudies-literature

Atomically-resolved interlayer charge ordering and its interplay with superconductivity in YBa2Cu3O6.81.

Project description:High-temperature superconductive (SC) cuprates exhibit not only a SC phase, but also competing orders, suppressing superconductivity. Charge order (CO) has been recognized as an important competing order, but its microscopic spatial interplay with SC phase as well as the interlayer coupling in CO and SC phases remain elusive, despite being essential for understanding the physical mechanisms of competing orders and hence superconductivity. Here we report the achievement of direct real-space imaging with atomic-scale resolution of cryogenically cleaved YBa2Cu3O6.81 using cross-sectional scanning tunneling microscopy/spectroscopy. CO nanodomains are found embedded in the SC phase with a proximity-like boundary region characterized by mutual suppression of CO and superconductivity. Furthermore, SC coherence as well as CO occur on both CuO chain and plane layers, revealing carrier transport and density of states mixing between layers. The CO antiphase correlation along the c direction suggests a dominance of Coulomb repulsion over Josephson tunneling between adjacent layers.

| S-EPMC8222377 | biostudies-literature