Magnetocapacitance

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

Large magnetocapacitance in electronic ferroelectric manganite systems

Abstract: We have observed a sizable positive magnetocapacitance ($\sim$$5-90\%$) in perovskite Pr$_{0.55}$Ca$_{0.45}$MnO$_3$ and bilayer Pr(Sr$_{0.1}$Ca$_{0.9}$)$_2$Mn$_2$O$_7$ system under 5T magnetic field across 20-100 K below the magnetic transition point T$_N$. The magnetodielectric effect, on the other hand, exhibits a crossover: (a) from positive to negative for the perovskite system and (b) from negative to positive for the bilayer system over the same temperature range. The bilayer Pr(Sr$_{0.1}$Ca$_{0.9}$)$_2$Mn$_2$O$_7$ system exhibits a sizable anisotropy as well. We have also noticed the influence of magnetic field on the dielectric relaxation characteristics of these systems. These systems belong to a class of improper ferroelectrics and are expected to exhibit charge/orbital order driven ferroelectric polarization below the transition point T$_{CO}$. Large magnetocapacitance in these systems shows typical multiferroic behavior even though the ferroelectric polarization is small in comparison to that of other ferroelectrics.

Effect of Sr substitution on structural, dielectric, magnetic and magnetoelectric properties of rapid liquid sintered BiFe0.8Ti0.2O3 ceramics

Abstract: Structural, dielectric, magnetic and magnetoelectric properties of polycrystalline Sr doped BiFe0.8Ti0.2O3 ceramics [Bi1−xSrx(Fe0.8Ti0.2)O3; x = 0.05, 0.10 and 0.15)] were studied. All the samples were prepared by rapid liquid phase sintering method. Rietveld refinement of X-ray diffraction patterns of all samples confirmed that the samples crystallize in a rhombohedral structure and showed change in Fe–O–Fe bond angle and Fe–O bond length which in turn enhanced magnetization from 0.33 to 0.73 emu/g with the increase in Sr concentration from x = 0.05 to 0.15. The dielectric constant and dielectric loss were observed to increase with the increase in temperature from 30 to 500 °C. An anomalous peak has been observed in dielectric constant versus temperature plot around 300 °C for all the samples, which is close to the magnetic transition temperature of BiFeO3. The composition-dependent magnetic properties with the expected Fe2+/Fe3+ ratio fluctuations were correlated by X-ray photoelectron spectroscopy. Magnetic and electric hysteresis loops showed a systematic increase in magnetization and polarization as a result of Sr doping in BiFe0.8Ti0.2O3 ceramics. The value of magnetocapacitance at 10 kHz was observed as 0.95, 1.23 and 1.73 for x = 0.05, 0.10, 0.15 respectively in Bi1−xSrxFe0.80Ti0.20O3 ceramics.

Modeling and Characterization of Smart LSMO Ferromagnetic Thin-Film Tunable Resistance

Abstract: This paper addresses the potential use of the (La0.67, Sr0.33)MnO3 (LSMO) ferromagnetic thin-film materials as microwave tunable enabling technology. LSMO thin-film materials have a strong interaction between their electrical and magnetic properties that could be translated into innovative tunable microwave components. The knowledge of the electroactive and magnetoactive properties of these materials is essential for modeling and design of novel microwave devices. The activity of these materials can be described by their electro/magnetoresistance and magnetocapacitance. The 400-nm-thick LSMO thin film is formed by the chemical solution deposition. Interdigital capacitor is chosen due to its high sensitivity for tunability and the fact that the metallization and patterning by photolithography are key issues in the fabrication of such structures which are formed by the deposition of metal on a single side of the LSMO thin film. The I-V relation, measured by tuning the bias voltage, is nonlinear and symmetric with respect to the polarity of the applied field. The switching to high resistive state is definite and sharp. Under electrostatic bias field, it is assumed that electric current flowing through narrow low-resistance path induces intense local magnetic field, resulting in the decrease of film resistance. This paper takes a close look in modeling the change of the LSMO resistance in terms of both working frequency and applied bias.

Self-consistent analysis of a quantum capacitor

Abstract: We analyze the behavior of the magnetocapacitance for a three-probe capacitor. The self-consistent evaluation of the internal potential is found to play a large role in determining quantitative values of the capacitance. For capacitor plates of mesoscopic size, this potential reduces the charge accumulation by more than an order of magnitude compared to that obtained with noninteracting models. However, the qualitative behavior of the magnetocapacitance is not substantially altered by the self-consistency. A simple but physically motivated model gives an analytical formula which compares well with the numerical data.