Magnetocapacitance

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

Electron subbands in a double quantum well in a quantizing magnetic field

Abstract: We employ magnetocapacitance and far-infrared spectroscopy techniques to study the spectrum of the double-layer electron system in a parabolic quantum well with a narrow tunnel barrier in the center. For gate-bias-controlled asymmetric electron density distributions in this soft two-subband system we observe both individual subband gaps and double-layer gaps at integer filling factor $\ensuremath{ u}.$ The bilayer gaps are shown to be either trivially common for two subbands or caused by the wave function reconstruction in growth direction as induced by intersubband electron transfer at a normal to the interface magnetic field. In the latter case the observed gaps at $\ensuremath{ u}=1$ and $\ensuremath{ u}=2$ are described within a simple model for the modified bilayer spectrum.

Magnetocapacitance and magnetoelectric coupling effect of Ni0.5Cu0.5Fe2O4/BaTiO3 mixed multiferroic fluids

Abstract: Ni0.5Cu0.5Fe2O4/BaTiO3 (NCFO/BTO) mixed multiferroic fluids were prepared by distributing surfactant treated NCFO and BTO particles in to a highly-insulating base fluid, the magnetocapacitance and magnetoelectric coupling effect were investigated. The results indicate that the sample shows strong magnetoelectric coupling effect, in which both the coercive field E c and remanent polarization P r enhance obviously under the action of magnetic field, while the dielectric constant decreases with increasing the magnetic field, revealing negative magnetocapacitance phenomenon. Large direct magnetolectric coupling coefficient was estimated to be α ~ 76 V/(cm−1.Oe), which is several orders of magnitude larger than that of conventional magnetoelectric composite ceramics. Further analysis indicates that the possibility of movement, aggregation and chain-like structure of the particles in the presence of external field is believed to be responsible for the observed negative magnetocapacitance and strong magnetoelectric coupling effect. The results show that the strong room temperature magnetoelectric effect of the mixed magnetoelectric fluids is the product of the deformation of the particle distribution and the utilization of clamping force under external field. This magnetoelectric coupling effect is different from that of conventional composite materials which is directly coupled via the interface interaction, which will be advantageous for practical applications.

Magnetic structures and magnetic phase transitions in the Mn-doped orthoferrite TbFeO3 studied by neutron powder diffraction

Abstract: The magnetic structures and the magnetic phase transitions in the Mn-doped orthoferrite TbFeO3 studied using neutron powder diffraction are reported. Magnetic phase transitions are identified at T-N(Fe/Mn) approximate to 295K where a paramagnetic-to-antiferromagnetic transition occurs in the Fe/Mn sublattice, T-SR(Fe/Mn) approximate to 26K where a spin-reorientation transition occurs in the Fe/Mn sublattice and T-N(R) approximate to 2K where Tb-ordering starts to manifest. At 295 K, the magnetic structure of the Fe/Mn sublattice in TbFe0.5Mn0.5O3 belongs to the irreducible representation Gamma(4) (G(x)A(y)F(z) or Pb'n'm). A mixed-domain structure of (Gamma(1) + Gamma(4)) is found at 250K which remains stable down to the spin re-orientation transition at T-SR(Fe/Mn) approximate to 26K. Below 26K and above 250 K, the majority phase (>80%) is that of Gamma(4). Below 10K the high-temperature phase Gamma(4) remains stable till 2K. At 2 K, Tb develops a magnetic moment value of 0.6(2) mu(B)/f.u. and orders long-range in F-z compatible with the Gamma(4) representation. Our study confirms the magnetic phase transitions reported already in a single crystal of TbFe0.5Mn0.5O3 and, in addition, reveals the presence of mixed magnetic domains. The ratio of these magnetic domains as a function of temperature is estimated from Rietveld refinement of neutron diffraction data. Indications of short-range magnetic correlations are present in the low-Q region of the neutron diffraction patterns at T < T-SR(Fe/Mn). These results should motivate further experimental work devoted to measure electric polarization and magnetocapacitance of TbFe0.5Mn0.5O3. (C) 2016 AIP Publishing LLC.