Browse
Submit Data
Databases
API
Help

Dataset Information

31 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Oxygen-vacancy-induced antiferromagnetism to ferromagnetism transformation in Eu₀.₅Ba₀.₅TiO₃₋δ multiferroic thin films.

ABSTRACT: Oxygen vacancies (V(O)) effects on magnetic ordering in Eu₀.₅Ba₀.₅TiO₃₋δ (EBTO₃₋δ) thin films have been investigated using a combination of experimental measurements and first-principles density-functional calculations. Two kinds of EBTO₃₋δ thin films with different oxygen deficiency have been fabricated. A nuclear resonance backscattering spectrometry technique has been used to quantitatively measure contents of the V(O). Eu₀.₅Ba₀.₅TiO₃ ceramics have been known to exhibit ferroelectric (FE) and G-type antiferromagnetic (AFM) properties. While, a ferromagnetic (FM) behavior with a Curie temperature of 1.85 K has been found in the EBTO₃₋δ thin films. Spin-polarized Ti(3+) ions, which originated from the V(O), has been proven to mediate a FM coupling between the local Eu 4f spins and were believed to be responsible for the great change of the magnetic ordering. Considering the easy formation of V(O), our work opens up a new avenue for achieving co-existence of FM and FE orders in oxide materials.

SUBMITTER: Li W

PROVIDER: S-EPMC3767944 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Correlation of High Magnetoelectric Coupling with Oxygen Vacancy Superstructure in Epitaxial Multiferroic BaTiO₃-BiFeO₃ Composite Thin Films.

Project description:Epitaxial multiferroic BaTiO₃-BiFeO₃ composite thin films exhibit a correlation between the magnetoelectric (ME) voltage coefficient αME and the oxygen partial pressure during growth. The ME coefficient αME reaches high values up to 43 V/(cm·Oe) at 300 K and at 0.25 mbar oxygen growth pressure. The temperature dependence of αME of the composite films is opposite that of recently-reported BaTiO₃-BiFeO₃ superlattices, indicating that strain-mediated ME coupling alone cannot explain its origin. Probably, charge-mediated ME coupling may play a role in the composite films. Furthermore, the chemically-homogeneous composite films show an oxygen vacancy superstructure, which arises from vacancy ordering on the {111} planes of the pseudocubic BaTiO₃-type structure. This work contributes to the understanding of magnetoelectric coupling as a complex and sensitive interplay of chemical, structural and geometrical issues of the BaTiO₃-BiFeO₃ composite system and, thus, paves the way to practical exploitation of magnetoelectric composites.

| S-EPMC5456545 | biostudies-literature

Induced Ferromagnetism in Epitaxial Uranium Dioxide Thin Films.

Project description:Actinide materials have various applications that range from nuclear energy to quantum computing. Most current efforts have focused on bulk actinide materials. Tuning functional properties by using strain engineering in epitaxial thin films is largely lacking. Using uranium dioxide (UO2 ) as a model system, in this work, the authors explore strain engineering in actinide epitaxial thin films and investigate the origin of induced ferromagnetism in an antiferromagnet UO2 . It is found that UO2+ x thin films are hypostoichiometric (x<0) with in-plane tensile strain, while they are hyperstoichiometric (x>0) with in-plane compressive strain. Different from strain engineering in non-actinide oxide thin films, the epitaxial strain in UO2 is accommodated by point defects such as vacancies and interstitials due to the low formation energy. Both epitaxial strain and strain relaxation induced point defects such as oxygen/uranium vacancies and oxygen/uranium interstitials can distort magnetic structure and result in magnetic moments. This work reveals the correlation among strain, point defects and ferromagnetism in strain engineered UO2+ x thin films and the results offer new opportunities to understand the influence of coupled order parameters on the emergent properties of many other actinide thin films.

| S-EPMC9685444 | biostudies-literature

Ultrasensitive interplay between ferromagnetism and superconductivity in NbGd composite thin films.

Project description:A model binary hybrid system composed of a randomly distributed rare-earth ferromagnetic (Gd) part embedded in an s-wave superconducting (Nb) matrix is being manufactured to study the interplay between competing superconducting and ferromagnetic order parameters. The normal metallic to superconducting phase transition appears to be very sensitive to the magnetic counterpart and the modulation of the superconducing properties follow closely to the Abrikosov-Gor'kov (AG) theory of magnetic impurity induced pair breaking mechanism. A critical concentration of Gd is obtained for the studied NbGd based composite films (CFs) above which superconductivity disappears. Besides, a magnetic ordering resembling the paramagnetic Meissner effect (PME) appears in DC magnetization measurements at temperatures close to the superconducting transition temperature. The positive magnetization related to the PME emerges upon doping Nb with Gd. The temperature dependent resistance measurements evolve in a similar fashion with the concentration of Gd as that with an external magnetic field and in both the cases, the transition curves accompany several intermediate features indicating the traces of magnetism originated either from Gd or from the external field. Finally, the signatures of magnetism appear evidently in the magnetization and transport measurements for the CFs with very low (<1 at.%) doping of Gd.

| S-EPMC4698659 | biostudies-literature

Solution-Processed Multiferroic Thin-Films with Large Magnetoelectric Coupling at Room-Temperature.

Project description:Experimental realization of thin films with a significant room-temperature magnetoelectric coupling coefficient, αME, in the absence of an external DC magnetic field, has been thus far elusive. Here, a large coupling coefficient of 750 ± 30 mV Oe-1 cm-1 is reported for multiferroic polymer nanocomposites (MPCs) thin-films in the absence of an external DC magnetic field. The MPCs are based on PMMA-grafted cobalt-ferrite nanoparticles uniformly dispersed in the piezoelectric polymer poly(vinylidene fluoride-co-trifluoroethylene, P(VDF-TrFE). It is shown that nanoparticle agglomeration plays a detrimental role and significantly reduces αME. Surface functionalization of the nanoparticles by grafting a layer of poly(methyl methacrylate) (PMMA) via atom transfer radical polymerization (ATRP) renders the nanoparticle miscible with P(VDF-TRFE) matrix, thus enabling their uniform dispersion in the matrix even in submicrometer thin films. Uniform dispersion yields maximized interfacial interactions between the ferromagnetic nanoparticles and the piezoelectric polymer matrix leading to the experimental demonstration of large αME values in solution-processed thin films, which can be exploited in flexible and printable multiferroic electronic devices for sensing and memory applications.

| S-EPMC10173693 | biostudies-literature

High-temperature antiferromagnetism in molecular semiconductor thin films and nanostructures.

Project description:The viability of dilute magnetic semiconductors in applications is linked to the strength of the magnetic couplings, and room temperature operation is still elusive in standard inorganic systems. Molecular semiconductors are emerging as an alternative due to their long spin-relaxation times and ease of processing, but, with the notable exception of vanadium-tetracyanoethylene, magnetic transition temperatures remain well below the boiling point of liquid nitrogen. Here we show that thin films and powders of the molecular semiconductor cobalt phthalocyanine exhibit strong antiferromagnetic coupling, with an exchange energy reaching 100 K. This interaction is up to two orders of magnitude larger than in related phthalocyanines and can be obtained on flexible plastic substrates, under conditions compatible with routine organic electronic device fabrication. Ab initio calculations show that coupling is achieved via superexchange between the singly occupied a1g () orbitals. By reaching the key milestone of magnetic coupling above 77 K, these results establish quantum spin chains as a potentially useable feature of molecular films.

| S-EPMC3941018 | biostudies-other

Strain evolution of each type of grains in poly-crystalline (Ba,Sr)TiO(3) thin films grown by sputtering.

Project description:The strain states of [111]-, [110]-, and [002]-oriented grains in poly-crystalline sputtered (Ba,Sr)TiO(3) thin films on highly [111]-oriented Pt electrode/Si substrates were carefully examined by X-ray diffraction techniques. Remarkably, [002]-oriented grains respond more while [110]- and [111]-oriented grains do less than the theoretically estimated responses, which is understandable from the arrangement of the TiO(6) octahedra with respect to the stress direction. Furthermore, such mechanical responses are completely independent of the degree of crystallization and film thickness. The transition growth temperature between the positive and negative strains was also different depending on the grain orientation. The unstrained lattice parameter for each type of grain was different suggesting that the oxygen vacancy concentration for each type of grain is different, too. The results reveal that polycrystalline (Ba,Sr)TiO(3) thin films are not an aggregation of differently oriented grains which simply follow the mechanical behavior of single crystal with different orientations.

| S-EPMC3516808 | biostudies-other

Complex strain evolution of polar and magnetic order in multiferroic BiFeO3 thin films.

Project description:Electric-field control of magnetism requires deterministic control of the magnetic order and understanding of the magnetoelectric coupling in multiferroics like BiFeO3 and EuTiO3. Despite this critical need, there are few studies on the strain evolution of magnetic order in BiFeO3 films. Here, in (110)-oriented BiFeO3 films, we reveal that while the polarization structure remains relatively unaffected, strain can continuously tune the orientation of the antiferromagnetic-spin axis across a wide angular space, resulting in an unexpected deviation of the classical perpendicular relationship between the antiferromagnetic axis and the polarization. Calculations suggest that this evolution arises from a competition between the Dzyaloshinskii-Moriya interaction and single-ion anisotropy wherein the former dominates at small strains and the two are comparable at large strains. Finally, strong coupling between the BiFeO3 and the ferromagnet Co0.9Fe0.1 exists such that the magnetic anisotropy of the ferromagnet can be effectively controlled by engineering the orientation of the antiferromagnetic-spin axis.

| S-EPMC6155110 | biostudies-literature

A First-Principles Study on the Multiferroic Property of Two-Dimensional BaTiO₃ (001) Ultrathin Film with Surface Ba Vacancy.

Project description:In this work, the multiferroic property of Ba-deficient BaTiO₃ (001) ultrathin film is studied employing the first-principles approach. The BaTiO₃ (001) ultrathin film is more energetically stable and behaves as a semiconductor relative to the (111) and (101) configurations, confirmed from the surface grand potential and electronic density of states. The electronic structures show that the O vacancy can switch the (001) film from a semi-conductor into a metal, while the Ba defect has a slight influence on the band gap, at a concentration of ~2.13%. In Ba-deficient (001) film, the spontaneous polarization pattern is changed and a spontaneous polarization parallel to the surface is observed. Furthermore, a magnetic moment is induced, and it is found to be originated from the O atoms in the supercell. Our results suggest that a strong magnetoelectric coupling occurs because the magnetic moment exhibits a 43.66% drop when the spontaneous polarization increases from 12.84 µC/cm² to 23.99 µC/cm² in the deficient BaTiO₃ with m = 2 under the bi-axial compress stress field.

| S-EPMC6410265 | biostudies-literature

Spatially Confined Spin Polarization and magnetic sublattice control in (La,Sr)MnO<sub>3-δ</sub> Thin Films by Oxygen Vacancy Ordering.

Project description:Perovskite oxides are known for their strong structure property coupling and functional properties such as ferromagntism, ferroelectricity and high temperature superconductivity. While the effect of ordered cation vacancies on functional properties have been much studied, the possibility of tuning the functionality through anion vacancy ordering has received much less attention. Oxygen vacancies in ferromagnetic La0.7Sr0.3MnO3-δ thin films have recently been shown to accumulate close to interfaces and form a brownmillerite structure (ABO2.5). This structure has alternating oxygen octahedral and tetrahedral layers along the stacking direction, making it a basis for a family of ordered anion defect controlled materials. We use density functional theory to study how structure and properties depend on oxygen stoichiometry, relying on a block-by-block approach by including additional octahedral layers in-between each tetrahedral layer. It is found that the magnetic and electronic structures follow the layers enforced by the ordered oxygen vacancies. This results in spatially confined electronic conduction in the octahedral layers, and decoupling of the magnetic sub-lattices in the octahedral and tetrahedral layers. These results demonstrate that anion defect engineering is a promising tool to tune the properties of functional oxides, adding a new avenue for developing functional oxide device technology.

| S-EPMC5491515 | biostudies-literature

Phase transitions via selective elemental vacancy engineering in complex oxide thin films.

Project description:Defect engineering has brought about a unique level of control for Si-based semiconductors, leading to the optimization of various opto-electronic properties and devices. With regard to perovskite transition metal oxides, O vacancies have been a key ingredient in defect engineering, as they play a central role in determining the crystal field and consequent electronic structure, leading to important electronic and magnetic phase transitions. Therefore, experimental approaches toward understanding the role of defects in complex oxides have been largely limited to controlling O vacancies. In this study, we report on the selective formation of different types of elemental vacancies and their individual roles in determining the atomic and electronic structures of perovskite SrTiO3 (STO) homoepitaxial thin films fabricated by pulsed laser epitaxy. Structural and electronic transitions have been achieved via selective control of the Sr and O vacancy concentrations, respectively, indicating a decoupling between the two phase transitions. In particular, O vacancies were responsible for metal-insulator transitions, but did not influence the Sr vacancy induced cubic-to-tetragonal structural transition in epitaxial STO thin film. The independent control of multiple phase transitions in complex oxides by exploiting selective vacancy engineering opens up an unprecedented opportunity toward understanding and customizing complex oxide thin films.

| S-EPMC4817049 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data