Magnetocapacitance without magnetism

Abstract

A substantial magnetodielectric effect is often an indication of coupled magnetic and elastic order, such as is found in the multi-ferroics. However, it has recently been shown that magnetism is not necessary to produce either a magnetoresistance or a magnetocapacitance when the material is inhomogeneous. Here, we will investigate the characteristic magnetic-field-dependent dielectric response of such an inhomogeneous system using exact calculations and numerical simulations of conductor–dielectric composites. In particular, we will show that even simple conductor–dielectric layers exhibit a magneto-capacitance, and thus random bulk inhomogeneities are not a requirement for this effect. Indeed, this work essentially provides a natural generalization of the Maxwell–Wagner effect to finite magnetic field. We will also discuss how this phenomenon has already been observed experimentally in some materials.

Complex magnetic structure and magnetocapacitance response in a non-oxide NiF2 system

“…These studies demonstrate that the non-oxide NiF 2 is a promising multifunctional material, showing rich magnetic, dielectric and negative magnetocapacitance (>90%) properties. The observation is large magnetocapacitance is attributed to the non-homogeneous grain distributions in NiF 2 bulk materials 42 . We hope our data would incite others to look for such effects in other non-oxide systems.…”

Magnetic field driven dielectric relaxation in non-magnetic composite medium: A low temperature study

“…In our case, there is no shift in relaxation peak by increasing magnetic field, and can't be explained completely by considering this model. On the other hand, Parish and Littlewood (PL) proposed that there is possibility to observe the dielectric relaxation [we have mentioned here 'relaxation' as it takes place at low frequency though PL used the term 'resonance'] in 2D inhomogeneous medium and interface between different conductive materials [7,20] by applying magnetic field without magnetism present in the system. The dielectric relaxation is observed due to the mixing of real and imaginary part of the dielectric response occurred by inhomogeneity of the medium.…”

Magnetoelectric Coupling Measurement Techniques in Multiferroic Materials

“…Dielectric constant (relative permittivity) measurements constitute an alternative method of detecting the magnetoelectric (ME) effect. This indirect method is based on the magnetodielectric effect (MDE) which describes a relationship between magnetic induction B and relative permittivity ε of a material [2,3,20,27]. Since a multiferroic compound relies on a magnetic field to influence its electric polarization, observable changes to its dielectric constant are to be expected.…”