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The dielectric response in a magnetic field is routinely used to probe the existence of coupled magnetic and elastic order in the multiferroics. However, here we demonstrate that magnetism is not necessary to produce a magnetocapacitance when the material is inhomogeneous. By considering a two-dimensional, two-component composite medium, we find a characteristic dielectric resonance that depends on magnetic field. We propose this as a possible signature of inhomogeneities and we argue that this behavior has already been observed in nanoporous silicon and some manganites.
The current critical review aims to be more than a simple summary and reproduction of previously published work. Many comprehensive reviews and collections can be found in the literature. The main intention is to provide an account of the progress ma
In a recent Letter, Berciu and Bhatt have presented a mean-field theory of ferromagnetism in III-V semiconductors doped with manganese, starting from an impurity band model. We show that this approach gives an unphysically broad impurity band and is
The silver chalcogenides provide a striking example of the benefits of imperfection. Nanothreads of excess silver cause distortions in the current flow that yield a linear and non-saturating transverse magnetoresistance (MR). Associated with the larg
We suggest an approach to account for spatial (composition) and thermal fluctuations in disordered magnetic models (e.g. Heisenberg, Ising) with given spatial dependence of magnetic spin-spin interaction. Our approach is based on introduction of fluc
We consider the transport of conserved charges in spatially inhomogeneous quantum systems with a discrete lattice symmetry. We analyse the retarded two point functions involving the charge and the associated currents at long wavelengths, compared to