The Experts below are selected from a list of 4758 Experts worldwide ranked by ideXlab platform

Nicola A. Spaldin - One of the best experts on this subject based on the ideXlab platform.

  • effect of epitaxial strain on the spontaneous polarization of thin film ferroelectrics
    Physical Review Letters, 2005
    Co-Authors: Claude Ederer, Nicola A. Spaldin
    Abstract:

    Epitaxial strain can substantially enhance the spontaneous polarizations and Curie temperatures of ferroelectric thin films compared to the corresponding bulk Materials. In this Letter we use first principles calculations to calculate the effect of epitaxial strain on the spontaneous polarization of the ferroelectrics , , and , and the Multiferroic Material . We show that the epitaxial strain dependence of the polarization varies considerably for the different systems, and in some cases is, in fact, very small. We discuss possible reasons for this different behavior and show that the effect of epitaxial strain can easily be understood in terms of the piezoelectric and elastic constants of the unstrained Materials. Our results provide a computational tool for the quantitative prediction of strain behavior in ferroelectric thin films.

  • Effect of epitaxial strain on the spontaneous polarization of thin film ferroelectrics
    Physical review letters, 2005
    Co-Authors: Claude Ederer, Nicola A. Spaldin
    Abstract:

    Epitaxial strain can substantially enhance the spontaneous polarizations and Curie temperatures of ferroelectric thin films compared to the corresponding bulk Materials. In this Letter we use first principles calculations to calculate the effect of epitaxial strain on the spontaneous polarization of the ferroelectrics ${\mathrm{BaTiO}}_{3}$, ${\mathrm{PbTiO}}_{3}$, and ${\mathrm{LiNbO}}_{3}$, and the Multiferroic Material ${\mathrm{BiFeO}}_{3}$. We show that the epitaxial strain dependence of the polarization varies considerably for the different systems, and in some cases is, in fact, very small. We discuss possible reasons for this different behavior and show that the effect of epitaxial strain can easily be understood in terms of the piezoelectric and elastic constants of the unstrained Materials. Our results provide a computational tool for the quantitative prediction of strain behavior in ferroelectric thin films.

  • first principles study of the Multiferroics bifeo3 bi2fecro6 and bicro3 structure polarization and magnetic ordering temperature
    Physical Review B, 2005
    Co-Authors: Pio Baettig, Claude Ederer, Nicola A. Spaldin
    Abstract:

    We present results of an ab initio density-functional theory study of three bismuth-based Multiferroics, BiFeO3 ,B i 2FeCrO6, and BiCrO3. We disuss differences in the crystal and electronic structure of the three systems and show that the application of the LDA+U method is essential to obtain realistic structural parameters for Bi2FeCrO6. We calculate the magnetic nearest-neighbor coupling constants for all three systems and show how Anderson’s theory of superexchange can be applied to explain the signs and relative magnitudes of these coupling constants. From the coupling constants we then obtain a mean-field approximation for the magnetic ordering temperatures. Guided by our comparison of these three systems, we discuss the possibilities for designing a Multiferroic Material with large magnetization above room temperature.

  • Influence of strain and oxygen vacancies on the magnetoelectric properties of Multiferroic bismuth ferrite
    Physical Review B - Condensed Matter and Materials Physics, 2005
    Co-Authors: Claude Ederer, Nicola A. Spaldin
    Abstract:

    The dependencies on strain and oxygen vacancies of the ferroelectric polarization and the weak ferromagnetic magnetization in the Multiferroic Material bismuth ferrite, BiFeO_3, are investigated using first principles density functional theory calculations. The electric polarization is found to be rather independent of strain, in striking contrast to most conventional perovskite ferroelectrics. It is also not significantly affected by oxygen vacancies, or by the combined presence of strain and oxygen vacancies. The magnetization is also unaffected by strain, however the incorporation of oxygen vacancies can alter the magnetization slightly, and also leads to the formation of Fe^{2+}. These results are discussed in light of recent experiments on epitaxial films of BiFeO_3 which reported a strong thickness dependence of both magnetization and polarization.

Claude Ederer - One of the best experts on this subject based on the ideXlab platform.

  • effect of epitaxial strain on the spontaneous polarization of thin film ferroelectrics
    Physical Review Letters, 2005
    Co-Authors: Claude Ederer, Nicola A. Spaldin
    Abstract:

    Epitaxial strain can substantially enhance the spontaneous polarizations and Curie temperatures of ferroelectric thin films compared to the corresponding bulk Materials. In this Letter we use first principles calculations to calculate the effect of epitaxial strain on the spontaneous polarization of the ferroelectrics , , and , and the Multiferroic Material . We show that the epitaxial strain dependence of the polarization varies considerably for the different systems, and in some cases is, in fact, very small. We discuss possible reasons for this different behavior and show that the effect of epitaxial strain can easily be understood in terms of the piezoelectric and elastic constants of the unstrained Materials. Our results provide a computational tool for the quantitative prediction of strain behavior in ferroelectric thin films.

  • Effect of epitaxial strain on the spontaneous polarization of thin film ferroelectrics
    Physical review letters, 2005
    Co-Authors: Claude Ederer, Nicola A. Spaldin
    Abstract:

    Epitaxial strain can substantially enhance the spontaneous polarizations and Curie temperatures of ferroelectric thin films compared to the corresponding bulk Materials. In this Letter we use first principles calculations to calculate the effect of epitaxial strain on the spontaneous polarization of the ferroelectrics ${\mathrm{BaTiO}}_{3}$, ${\mathrm{PbTiO}}_{3}$, and ${\mathrm{LiNbO}}_{3}$, and the Multiferroic Material ${\mathrm{BiFeO}}_{3}$. We show that the epitaxial strain dependence of the polarization varies considerably for the different systems, and in some cases is, in fact, very small. We discuss possible reasons for this different behavior and show that the effect of epitaxial strain can easily be understood in terms of the piezoelectric and elastic constants of the unstrained Materials. Our results provide a computational tool for the quantitative prediction of strain behavior in ferroelectric thin films.

  • first principles study of the Multiferroics bifeo3 bi2fecro6 and bicro3 structure polarization and magnetic ordering temperature
    Physical Review B, 2005
    Co-Authors: Pio Baettig, Claude Ederer, Nicola A. Spaldin
    Abstract:

    We present results of an ab initio density-functional theory study of three bismuth-based Multiferroics, BiFeO3 ,B i 2FeCrO6, and BiCrO3. We disuss differences in the crystal and electronic structure of the three systems and show that the application of the LDA+U method is essential to obtain realistic structural parameters for Bi2FeCrO6. We calculate the magnetic nearest-neighbor coupling constants for all three systems and show how Anderson’s theory of superexchange can be applied to explain the signs and relative magnitudes of these coupling constants. From the coupling constants we then obtain a mean-field approximation for the magnetic ordering temperatures. Guided by our comparison of these three systems, we discuss the possibilities for designing a Multiferroic Material with large magnetization above room temperature.

  • Influence of strain and oxygen vacancies on the magnetoelectric properties of Multiferroic bismuth ferrite
    Physical Review B - Condensed Matter and Materials Physics, 2005
    Co-Authors: Claude Ederer, Nicola A. Spaldin
    Abstract:

    The dependencies on strain and oxygen vacancies of the ferroelectric polarization and the weak ferromagnetic magnetization in the Multiferroic Material bismuth ferrite, BiFeO_3, are investigated using first principles density functional theory calculations. The electric polarization is found to be rather independent of strain, in striking contrast to most conventional perovskite ferroelectrics. It is also not significantly affected by oxygen vacancies, or by the combined presence of strain and oxygen vacancies. The magnetization is also unaffected by strain, however the incorporation of oxygen vacancies can alter the magnetization slightly, and also leads to the formation of Fe^{2+}. These results are discussed in light of recent experiments on epitaxial films of BiFeO_3 which reported a strong thickness dependence of both magnetization and polarization.

F. A. Mikailzade - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic phase composition of strontium titanate implanted with iron ions
    Materials Research Bulletin, 2011
    Co-Authors: E.n. Dulov, N.g. Ivoilov, O.a. Strebkov, L. R. Tagirov, V. I. Nuzhdin, R.i. Khaibullin, Sinan Kazan, F. A. Mikailzade
    Abstract:

    Abstract Thin magnetic films were synthesized by means of implantation of iron ions into single-crystalline (1 0 0) substrates of strontium titanate. Depth-selective conversion electron Mossbauer spectroscopy (DCEMS) indicates that origin of the samples magnetism is α-Fe nanoparticles. Iron-substituted strontium titanate was also identified but with paramagnetic behaviour at room temperature. Surface magneto-optical Kerr effect (SMOKE) confirms that the films reveal superparamagnetism (the low-fluence sample) or ferromagnetism (the high-fluence sample), and demonstrate absence of magnetic in-plane anisotropy. These findings highlight iron implanted strontium titanate as a promising candidate for composite Multiferroic Material and also for gas sensing applications.

A. Ashida - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic frustration behavior of ferroelectric ferromagnet YbMnO3 epitaxial films
    Journal of Applied Physics, 2007
    Co-Authors: Norifumi Fujimura, Takeshi Yoshimura, Takeshi Takahashi, A. Ashida
    Abstract:

    YbMnO3 has an antiferromagnetic (AFM) and field-induced ferromagnetic transitions at 80 and 3K, respectively. It also exhibits a ferroelectric transition at much higher temperature (∼1000K), making it a rare example of systems having both ferroelectric and ferromagnetic transitions. In the present study, magnetic field induced ferromagnetism of an YbMnO3 epitaxial film was recognized at 80K, which is much higher temperature than that of single crystal. The magnetic frustration behaviors were also observed below 87K. Regarding the cross-correlation phenomena, a coupling between the ferroelectric domain switching and the AFM spin ordering is demonstrated using a real Multiferroic Material, YbMnO3 epitaxial film.

  • Multiferroic behaviour of YMnO3 and YbMnO3 epitaxial films
    Philosophical Magazine Letters, 2007
    Co-Authors: Norifumi Fujimura, Takeshi Yoshimura, A. Ashida, Takeshi Takahashi, N. Shigemitsu, H Fukumura, Hiroshi Harima
    Abstract:

    YMnO3 has an antiferromagnetic (AFM) transition at 76 K with a ferroelectric (FE) transition at much higher temperature. For that reason, it is a so-called Multiferroic Material. Recently, anomalies in the relative dielectric permittivity in YMnO3 near the Neel temperature were recognized. In the present study, coupling between the ferroelectric domain switching and the AFM spin ordering is demonstrated. On the other hand, magnetic field-induced ferromagnetism was recognized in a ferroelectric YbMnO3 epitaxial film. The magnetic frustration behaviour of this ferroelectric and ferromagnetic YbMnO3, a real Multiferroic Material, is also described.

Y Onose - One of the best experts on this subject based on the ideXlab platform.

  • surface acoustic wave coupled to magnetic resonance on Multiferroic cub 2 o 4
    Physical Review B, 2019
    Co-Authors: Ryo Sasaki, Yoichi Nii, Y Onose
    Abstract:

    We observed surface acoustic wave (SAW) propagation on a Multiferroic Material ${\mathrm{CuB}}_{2}{\mathrm{O}}_{4}$ with use of two interdigital transducers (IDTs). The period of IDT fingers is as short as 1.6 $\ensuremath{\mu}\mathrm{m}$ so that the frequency of SAW is 3 GHz, which is comparable with that of magnetic resonance. In the antiferromagnetic phase, the SAW excitation intensity varied with the magnitude and direction of the magnetic field, owing to the dynamical coupling between SAWs and antiferromagnetic resonance of ${\mathrm{CuB}}_{2}{\mathrm{O}}_{4}$. The microscopic mechanism is discussed based on the symmetrically allowed magnetoelastic coupling.