Atomic scale chemical fluctuation in LaSrVMoO6: A proposed halfmetallic antiferromagnet

Half metallic antiferromagnets (HMAFM) have been proposed theoretically long ago but have not been realized experimentally yet. Recently, a double perovskite compound, LaSrVMoO6, has been claimed to be an almost real HMAFM system. Here, we report detailed experimental and theoretical studies on this compound. Our results reveal that the compound is neither a half metal nor an ordered antiferromagnet. Most importantly, an unusual chemical fluctuation is observed locally, which finally accounts for all the electronic and magnetic properties of this compound.Comment: 10 pages, 3 figures, 3 table

Pressure-induced delocalization in intermetallic system UMn2Ge2

The electronic and magnetic structures of the ternary intermetallic UMn2Ge2 ferromagnet are self-consistently calculated as a function of pressure within the local spin density approximation (LSDA) to the density functional theory (DFT) using the augmented spherical wave (ASW) method..

Magnetic ground state of UCu2X2 (X=Si, Ge) from first principles

The electronic and magnetic structures of UCu2X2 germanide and silicide are revisited in view of existing controversy from experimental findings..

Origin of enhanced piezoelectric properties revealed through electric field driven studies in 0.94(Na0.5Bi0.5TiO3)−0.06(Ba0.85Ca0.15Ti0.9Zr0.1O3) ceramics

A single phase 0.94(Na0.5Bi0.5TiO3)-0.06(Ba0.85Ca0.15Ti0.9Zr0.1O3) solid solution (i.e., BCZT-0.06) is prepared using a conventional solid-state sintering route with enhanced piezo and ferroelectric properties as compared to Na0.5Bi0.5TiO3 (NBT). In the context of understanding the origin of enhanced piezoelectric properties in a BCZT-0.06 specimen, electric field driven studies on different length scales, viz., global, local, and electronic structure, are carried out using x-ray/neutron diffraction, Raman scattering, and UV-Vis spectroscopic techniques. An analysis on different length scales of the electric field-driven BCZT-0.06 specimen displays minimum rhombohedral lattice distortion (δr), reduced homogeneous lattice strain (δ), octahedral strain (ζ), and pronounced Ti-cation displacement along the polar [111] direction as compared to parent NBT. The enhanced ferro and piezoelectric responses observed in the BCZT-0.06 specimen have been attributed to the ease of non-180° domain re-orientation, domain switching, and domain wall motion due to reduced strain coupled with a polarization extension mechanism

Onsite Magnetic Moment through Cation Distribution and Magnetocrystalline Anisotropy Studies in NiFe2-xRxO4 (R = Y and Lu; x = 0, 0.05, and 0.075)

Onsite magnetic moments through cation distribution and magnetocrystalline anisotropy studies of NiFe2−xRxO4 (R = Y and Lu; x = 0, 0.05, and 0.075) compounds were investigated, and the results are discussed and presented in this paper. All the compounds were prepared by solid state reaction, and the compounds formed in the cubic inverse spinel phase with the space group Fd3¯m. The cation distribution, bond lengths, u-parameter, etc. were estimated through the Rietveld refinement of XRD patterns. Increment in the lattice constant was observed upon partial substitution of Fe3+ by Y3+/Lu3+. The presence of all elements and their ionic states were confirmed from X-ray photoelectron spectroscopy studies. Analyses of Mössbauer spectra revealed that the hyperfine fields and the magnetic moments at the B-site (and hence net moment) decreased with increasing Y3+/Lu3+ occupancy and that the compounds exhibited a Néel-type, collinear ferrimagnetic structure. Magnetization measurements revealed that the magnetic moment decreased with Y3+/Lu3+ substitution. The high field regimes of the magnetization curves were modeled using the law of approach to the saturation magnetization equation, and the first order cubic anisotropy constants (K1) were calculated. The temperature variation of K1 and effects of Y3+/Lu3+ substitution are explaine

Fluorinated hexagonal 4H SrMnO 3 : a locally disordered manganite

The structural, magnetic and dielectric properties of the hexagonal four-layered form of SrMnO 3 along with its fluorinated counterpart have been investigated. Among these, the fluorinated hexagonal four-layered compound is being reported for the first time. Although the bulk crystal structure does not change with fluorination, there are clear spectroscopic evidences of local chemical fluorination having disordered Mn-F rich phases in the fluorinated compound. Fluorination of bulk antiferromagnetic SrMnO 3 changes the magnetic properties considerably where a spin- or cluster-glass-like state appears below 42 K with a large exchange bias. In addition to that, the F-doped SrMnO 3 indicates development of polarization and the system exhibits ferroelectric nature which has been confirmed through the strain-electric field (S-E) hysteresis loop

Nonmonotonic Magnetic Field Dependence of Remnant Ferroelectric Polarization in Reduced Graphene Oxide-BiFeO3 Nanocomposite

The thin-film heterostructures or nanocomposites exhibit vastly different properties from those observed in bulk systems. Herein, in a nanocomposite of reduced graphene oxide (RGO) and BiFeO3 (BFO), the remnant ferroelectric polarization is found to follow nonmonotonic magnetic field dependence at room temperature as the applied magnetic field is swept across 0-20 kOe on a pristine sample. Bulk BiFeO3, in contrast, exhibits monotonic suppression of polarization under magnetic field. The remanent ferroelectric polarization, in the present case, is determined, primarily, from powder neutron diffraction patterns recorded under 0-20 kOe field. The nanosized (approximate to 20 nm) particles of BFO are anchored onto the graphene sheets of RGO via Fe-C bonds with concomitant rise in covalency in the Fe-O bonds. Field-dependent competition between positive and negative magnetoelectric coupling arising from magnetostriction due to, respectively, interface and bulk magnetization appears to have given rise to the observed nonmonotonic field dependence of polarization. The emergence of Fe-C bonds and consequent change in the magnetic and electronic structure of the interface region have influenced coupling between ferroelectric and magnetic properties remarkably and thus creates a new way of tuning the magnetoelectric properties via reconstruction of interfaces in nanocomposites or heterostructures of graphene/single-phase-multiferroic systems