Magnetocapacitance

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

Edge channels in integer and fractional quantum-Hall regime investigated by magnetocapacitance

Abstract: We have evaluated the width of edge channels in the fractional and integer quantum-Hall (QH) regime by the magnetocapacitance measurement between a gate and two-dimensional electron system in GaAs/AlGaAs heterostructures. The frequency dependence of the magnetocapacitance between 100 Hz and 1 MHz has been measured at temperatures between 35 mK and 0.4 K. At the fractional QH regime, the total width of the edge channels is found to be 2.5 and 9 μm at 35 mK at the QH plateaux of filling factor ν= 1 3 and 2 3 , respectively. In the integer QH regime, the temperature dependence of the edge channel width is almost flat in the range of 35 mK–0.4 K. At the QH plateau of ν=1 due to spin-splitting Landau level, the width of total edge channel is almost the same value with that at ν=2. The width at ν=3 is also comparable to that at ν=4, although the residual bulk conductivity of ν=3 is an order of magnitude larger than that of ν=4.

Electrically heterogeneous high dielectric BaTi 0.4 (Fe 0.5 Nb 0.5 ) 0.6 O 3 ceramic

Abstract: The effect of sintering temperatures on the lattice parameters, microstructure and electrical properties of BaTi 0.4 (Fe 0.5 Nb 0.5 ) 0.6 O 3 perovskite ceramics were investigated. Impedance spectroscopy analysis confirms that this material is electrically heterogeneous which plays a major role for the high dielectric constant. The sintering temperatures have a sensitive influence on the values of the dielectric constant. High dielectric constant (12,708) with low dielectric loss (0.23) was achieved at room temperature for 1250 °C sintered ceramic. Activation energy was found to be 0.25 eV and 0.31 eV corresponding to grain and grain boundary, respectively which confirms that the grain boundaries are more insulating than grains. We observed the high magnetocapacitance (5.8%) at 9 kOe for 1250 °C sintered sample which is useful for the practical application. This study will help to modify the BaFe 0.5 Nb 0.5 O 3 based materials and lead to more applications in the microelectronics devices.

Energetics of the complex phase diagram of a tunable bilayer graphene probed by quantum capacitance

Abstract: Bilayer graphene provides a unique platform to explore the rich physics in quantum Hall effect. The unusual combination of spin, valley, and orbital degeneracy leads to interesting symmetry-broken states with electric and magnetic field. Conventional transport measurements, like resistance measurements, have been performed to probe the different ordered states in bilayer graphene. However, not much work has been done to directly map the energetics of those states in bilayer graphene. Here, we have carried out the magnetocapacitance measurements with electric and magnetic field in a hexagonal boron nitride encapsulated dual-gated bilayer graphene device. At zero magnetic field, using the quantum capacitance technique we measure the gap around the charge neutrality point as a function of perpendicular electric field and the obtained value of the gap matches well with the theory. In the presence of a perpendicular magnetic field, we observe Landau-level crossing in our magnetocapacitance measurements with electric field. The gap closing and reopening of the lowest Landau level with electric and magnetic field shows the transition from one ordered state to another. Furthermore, we observe the collapsing of the Landau levels near the band edge at higher electric field ($\overline{D}g0.5$ V/nm), which was predicted theoretically. The complete energetics of the Landau levels of bilayer graphene with electric and magnetic field in our experiment paves the way to unravel the nature of ground states of the system.

Beats of the magnetocapacitance oscillations in lateral semiconductor superlattices

Abstract: We present calculations on the magnetocapacitance of the two-dimensional electron gas in a lateral semiconductor superlattice under two-dimensional weak periodic potential modulation in the presence of a perpendicular magnetic field. Adopting a Gaussian broadening of magnetic-field-dependent width in the density of states, we present explicit and simple expressions for the magnetocapacitance, valid for the relevant weak magnetic fields and modulation strengths. As the modulation strength in both directions increase, beats of the magnetocapacitance oscillations are observed, in the low magnetic field range (Weiss-oscillations regime), which are absent in the one-dimensional weak modulation case.

Magnetodielectric Effect in Relaxor Ceramic Pb(In0.5Nb0.5)O3

Abstract: We have studied the magnetodieletric response of polycrystalline samples of the perovskite relaxor ferroelectric Pb(In0.5Nb0.5)O3. Dielectric anomalies of ϵ′ and ϵ′ are clearly observed at the phase transition from ferroelectric rhombohedral phase to rhombic antiferroelectric phase (TC = 36°C) and then at the phase transition from antiferroelectric phase to cubic paraelectric phase (TN = 175°C). At room temperature both ϵ′ and ϵ′ are decreased under an applied static magnetic field at all measuring frequencies in the range of 25 Hz – 5 kHz. Magnetocapacitance of −15% was observed at 25 Hz and it is decreased to −1.5% at 5 kHz. The magnetodielectric effect in the ferroelectric state appears to originate from interaction of the external magnetic field with magnetic moments of moving ferroelectric domain walls.