Showing papers on "Magnetocapacitance published in 2003"
TL;DR: The discovery of ferroelectricity in a perovskite manganite, TbMnO3, where the effect of spin frustration causes sinusoidal antiferromagnetic ordering and gigantic magnetoelectric and magnetocapacitance effects are found.
Abstract: The magnetoelectric effect--the induction of magnetization by means of an electric field and induction of polarization by means of a magnetic field--was first presumed to exist by Pierre Curie, and subsequently attracted a great deal of interest in the 1960s and 1970s (refs 2-4). More recently, related studies on magnetic ferroelectrics have signalled a revival of interest in this phenomenon. From a technological point of view, the mutual control of electric and magnetic properties is an attractive possibility, but the number of candidate materials is limited and the effects are typically too small to be useful in applications. Here we report the discovery of ferroelectricity in a perovskite manganite, TbMnO3, where the effect of spin frustration causes sinusoidal antiferromagnetic ordering. The modulated magnetic structure is accompanied by a magnetoelastically induced lattice modulation, and with the emergence of a spontaneous polarization. In the magnetic ferroelectric TbMnO3, we found gigantic magnetoelectric and magnetocapacitance effects, which can be attributed to switching of the electric polarization induced by magnetic fields. Frustrated spin systems therefore provide a new area to search for magnetoelectric media.
3,769 citations
TL;DR: In this article, the structural, magnetic, and electric properties of ferromagnetic perovskite structures were investigated and the changes in the dielectric constant were induced by the magnetic ordering.
Abstract: We have investigated the structural, magnetic, and electric properties of ferromagnetic ${\mathrm{BiMnO}}_{3}$ with a highly distorted perovskite structure. At ${T}_{E}=750--770\mathrm{K},$ a centrosymmetric--to--non-centrosymmetric structural transition takes place, which describes of the ferroelectricity in the system. The changes in the dielectric constant were induced by the magnetic ordering ${(T}_{M}\ensuremath{\approx}100\mathrm{K})$ as well as by the application of magnetic fields near ${T}_{M}.$ These features are attributed to the inherent coupling between the ferroelectric and ferromagnetic orders in the multiferroic system.
898 citations
TL;DR: The large magnetocapacitance near the transition temperature in the ferromagnet SeCuO3 suggests routes to enhancing the magnetodielectric response for practical applications.
Abstract: We report on the effects of spin fluctuations, magnetic ordering, and external magnetic field on the dielectric constant of the ferromagnet SeCuO3, and the antiferromagnet TeCuO3. A model based on the coupling between uniform polarization and the q-dependent spin-spin correlation function is presented to explain the different behaviors for these isostructural compounds. The large magnetocapacitance near the transition temperature in the ferromagnet SeCuO3 suggests routes to enhancing the magnetodielectric response for practical applications.
207 citations
TL;DR: In this article, the chemical potential jump in a strongly correlated two-dimensional electron system in silicon when the filling factor traverses the valley gap at $\ensuremath{
u} = 1$ and $\ensuresuremath{nu}= 3.$ was determined.
Abstract: Using magnetocapacitance data, we directly determine the chemical potential jump in a strongly correlated two-dimensional electron system in silicon when the filling factor traverses the valley gap at $\ensuremath{
u}=1$ and $\ensuremath{
u}=3.$ The data yield a valley gap that is strongly enhanced compared to the single-particle value and increases linearly with magnetic field. This result has not been explained by existing theories.
46 citations
TL;DR: Using magnetocapacitance data in tilted magnetic fields, this work directly determines the chemical potential jump in a strongly correlated two-dimensional electron system in silicon when the filling factor traverses the spin and the cyclotron gaps.
Abstract: Using magnetocapacitance data in tilted magnetic fields, we directly determine the chemical potential jump in a strongly correlated two-dimensional electron system in silicon when the filling factor traverses the spin and the cyclotron gaps The data yield an effective g factor that is close to its value in bulk silicon and does not depend on the filling factor The cyclotron splitting corresponds to the effective mass that is strongly enhanced at low electron densities
23 citations
TL;DR: In this article, the spatial distribution of edge states in the quantum Hall (QH) regime has been investigated by the magnetocapacitance measured with the multigate of thin wires along the sample boundary.
Abstract: The spatial distribution of the edge states in the quantum Hall (QH) regime has been investigated by the magnetocapacitance measured with the multigate of thin wires along the sample boundary. We have observed the compressible electronic states which exist within about $1\ensuremath{\mu}\mathrm{m}$ along the sample boundary in the QH regime. The edge states become broad by more than a few microns when the negative side gate bias is applied to the outermost gate wire.
10 citations