Magnetocapacitance

About: Magnetocapacitance is a research topic. Over the lifetime, 497 publications have been published within this topic receiving 23846 citations.

Density of states of the two-dimensional electron gas studied by magnetocapacitances of biased double-barrier structures.

Abstract: The magnetocapacitive response of a double-barrier structure (DBS), biased beyond resonances, has been employed to determine the density of states (DOS) of the two-dimensional electron gas residing in the accumulation layer on the incident side of the DBS. An adequate procedure is developed to compare the model calculation of the magnetocapacitance with the experimental C vs B curves measured at different temperatures and biases. The results show that the fitting is not only self-consistent but also remarkably good even in well-defined quantum Hall regimes. As a result, information about the DOS in strong magnetic fields could reliably be extracted.

Role of the spin-pair correlation in magnetic relaxor ferroelectrics

Abstract: In magnetic relaxor ferroelectrics, for the coupling interaction between the relaxor ferroelectricity and magnetic order, the dielectric susceptibility exhibits a sharp increase around the magnetic phase transition temperature. By adding an appropriate coupling term between the electrical and magnetic subsystems, which is related to the interaction of the Heisenberg spin and the order parameter field, the replica theory based on the spherical random-bond-random-field model and the mean-field theory based on the Heisenberg model are successfully applied to the magnetic relaxor ferroelectrics. We find that the fluctuation of the spin-pair correlation plays an important role in the change of dielectric susceptibility around the magnetic phase transition temperature. The obtained static dielectric susceptibility and the magnetocapacitance are in good agreement with the experimental results.

Electronic, thermoelectric, and magneto-dielectric properties of Ca1−xNaxCr2O4

Abstract: We report on electronic, thermoelectric, and magneto-dielectric properties of Ca1−xNaxCr2O4 series with a calcium ferrite-type structure prepared by high-pressure-high-temperature synthesis. Dielectric spectroscopy down to 2 K confirms that both CaCr2O4 and NaCr2O4 end members have an insulating ground state notwithstanding the fact that the latter compound has a mixed valence Cr3+/Cr4+ structure. A crossover from positive to negative charge carriers occurs in NaCr2O4 at T≈230 K. Partial substitution of Ca for Na brings about a change from n to p type carriers at ca. x=0.75. A strong suppression of thermal conductivity below TN=21 K was found in CaCr2O4 indicating a scattering of acoustic phonons from a long wave-length cycloidal magnetic excitations. A pronounced dielectric anomaly at Neel temperature adds CaCr2O4 to the multiferroic family of compounds. Lattice contribution to dielectric properties of NaCr2O4 at TN=125 K is screened by high electric conductivity. An onset of the magnetocapacitance above...

Width of compressible strips in quantum Hall regime

Abstract: We have investigated the width of the compressible strips in the edge state by magnetocapacitance between two-dimensional electron gas and a metal gate. The detail of Landau level filling factor dependence of the width is measured around the quantum Hall plateaux, and the influence of confinement potential on the width has been studied by tuning the side gate voltage. It is confirmed that the width is mainly governed by the depletion region at the sample boundary; the spatially gentle confinement potential forms wider compressible and incompressible strips. The nonlocal resistance has been also studied in the samples with tunable confinement potential by side gate, which supports the result of the capacitance measurement.

Investigations on Magnetoelectric and Magnetodielectric Properties of CMFO–PBT Composites

Abstract: The present paper reports the dielectric, magnetodielectric, and magnetoelectric properties of Mn-substituted Co1.2−x Mn x Fe1.8O4 (CMFO) and Pb0.2Ba0.8TiO3 (PBT) magnetoelectric (ME) composites. The Co1.2−x Mn x Fe1.8O4 is initially studied for variation of electrical resistivity ρ, saturation magnetization M s, permeability μ, coercive field H c, and coefficient of magnetostriction λ to determine compositions suitable to form the ME composite. Here, x = 0.4 and 0.1 are observed to possess optimum values of ρ, M s, μ, H c, and λ; therefore, the composites are formed using Co0.8Mn0.4Fe1.8O4 (CMFO 0.4) as well as Co1.1Mn0.1Fe1.8O4 (CMFO 0.1). The composites were synthesized and investigated for their structural, dielectric, magnetoelectric, and magnetodielectric properties. The dielectric constant of the composites is observed to exhibit a contribution due to interfacial polarization as well as a contribution due to the PBT phase. The variation of the linear magnetoelectric coefficient, α, quadratic magnetoelectric coefficient, β, and magnetocapacitance, M c, for various compositions are reported in this paper. The paper also reports the effect of sintering temperature and variation of frequency on the magnitude of α and M c. The samples with y = 0.5 are observed to show a sufficiently large and useful magnitude of magnetoelectric coefficients and M c value.