Magnetocapacitance

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

Strain-induced effects on antiferromagnetic ordering and magnetocapacitance in orthorhombic HoMnO(3) thin films.

Abstract: We investigated the magnetic and ferroelectric properties of c-axis oriented orthorhombic phase HoMnO3 (o-HMO in Pbnm symmetry setting) thin films grown on Nb-doped SrTiO3(001) substrates. The o-HMO films exhibit an antiferromagnetic ordering near 42 K, irrespective of the orientation of the applied field. However, an additional magnetic ordering occurring around 35 K was observed when the field was applied along the c-axis of o-HMO, which was absent when the field was applied in the ab-plane. The magnetocapacitance measured along the c-axis showed that although there is evidence of dielectric constant enhancement when the temperature is below 35 K the expected abrupt change in dielectric constant appears at a much lower temperature and reaches maximum around 13.5 K, indicating that the low-temperature c-axis polarization might be related to the ordering of the Ho3+ moment. The lattice constant analyses using x-ray diffraction and the observation of a slight magnetization hysteresis suggest that the weak second magnetic transition along the c-axis at 35 K might be more relevant to the strain-induced effect on antiferromagnetism.

Sensitivity and Noise Evaluation of a Bonded Magneto(elasto) Electric Laminated Sensor Based on In-Plane Magnetocapacitance Effect for Quasi-Static Magnetic Field Sensing

Abstract: The quasi-static magnetic field detection of a layer-bonded magneto(elasto) electric (ME) laminate has been investigated by measuring the in-plane electric capacitance via its interdigital electrodes close to the piezoelectric resonant frequency. The ME-layered composite is considered as a stress-induced dielectric effect because there is practically no direct response of the electric capacitance to an external magnetic field. The sensitivity is dominated by the magnetoelastic coupling in the magnetic layer and on the stress induced by the permittivity change in the piezoelectric layer. The low-frequency magnetocapacitance effect is sensitive to an external magnetic bias which can modulate the electric permittivity by producing a stress. The magnetoelastic coupling is another important parameter for this magnetic field detection mode. For a given magnetic field, the amplitude of the magnetostriction is directly related to this parameter as well. Therefore, an optimal magnetic bias can maximize the induced strain or stress which is coupled into the piezoelectric layer through the change of the electric permittivity in this layer. To evaluate the sensitivity and the noise performance by the magnetocapacitance effect, we have used the piezoelectric and magnetic constitutive equations to predict the permittivity dependence. Experimentally, this sensor achieved an equivalent magnetic noise spectral density, presently still limited, by the noise of the detection electronics, $\sim 100$ pT/ $\surd $ Hz at 1 Hz and offered a dc detection capability. With the model and experimental nonlinear factors, an equivalent sensor noise spectral density close to the pT/ $\surd $ Hz can be ultimately predicted considering the mechanical loss limitation of the sensor.

Colossal magnetocapacitance near room temperature in ferromagnetic Cr2O3 film

Abstract: We report significantly large magnetocapacitance (∼32%) close to room temperature in Cr2O3 film fabricated using pulsed laser deposition technique. Magnetic hysteresis loop exhibits typical signature of a soft ferromagnetic character at room temperature in contrast to that observed in antiferromagnetic bulk counterpart. The value of saturation magnetization (MS) is significantly large with MS≈1.0μB at room temperature. A significant strain ascribed to the lattice mismatch is suggested for the occurrence of ferromagnetism and is correlated to the significant magnetocapacitance close to room temperature.