A negative dielectric constant in nano-particle materials under an electric field at very low frequencies

Abstract

The significance of a negative dielectric constant has long been recognized. We report here the observation of a fieldinduced large negative dielectric constant of aggregates of oxide nano-particles at frequencies below ~ 1 Hz at room temperature. The accompanying induced charge detected opposes the electric field applied in the field-induced negative dielectric constant state. A possible collective effect in the nano-particle aggregates is proposed to account for the observations. Materials with a negative dielectric constant are expected to provide an attraction between similar charges and unusual scattering to electromagnetic waves with possible profound implications for high temperature superconductivity and communications.Keywords: negative dielectric constant, negative polarization, diaelectricity, nanoparticles, electrorheology A NEGATIVE STATIC DIELECTRIC CONSTANTAccording to the BCS theory, the superconducting transition temperature T c is equal to 1.14θ D exp [-1/N(0)V], where θ D is the Debye temperature (or the characteristic temperature of other quasi-particles), N(0) is the electron density of states at the Fermi energy, and V is the attractive interaction between the electrons (or other quasi-particles). It is evident that the greater the V is, the higher the T c is. Various propositions have been advanced over the years prior to the discovery of cuprate high temperature superconductivity to enhance V and thus T c . 1 The main interaction between two electric charges, q 1 and q 2 , separated by a distance r, is known to be V(r) = q 1 q 2 /ε'r, where ε' is the real part of the dielectric constant ε = ε' − iε". A negative static dielectric constant, ε'(k,ω) at a wave-vector k ≠ 0 and frequency ω = 0, has attracted great interest because of its implications for wave propagation, electrolyte behavior, colloidal properties, and bio-membrane functions in addition to possible high temperature superconductivity. For a negative ε', the force between two electrons will be attractive, leading to electron-pairing if other electron instabilities can be arrested.2 Electron-pairing has been demonstrated to be responsible for superconductivity in the conventional low temperature superconductors as well as in the newly discovered high temperature superconductors. A route via a negative ε' to higher T c may be worth exploring.The analogy between magnetism and electricity has long been established by Maxwell in the 19th century, in spite of their subtle difference. While magnetic materials display paramagnetism, ferromagnetism, antiferromagnetism, and diamagnetism, only paraelectricity, ferroelectricity, and antiferrolelectricity have been found in dielectric materials. The missing "diaelectricity" may therefore be found in a dielectric material that is characterized by a negative dielectric susceptibility ε'-1 and a polarization opposing the electric field.For the above reasons, we have decided to examine materials that may display a negative ε'.

High-Temperature Superconductivity in a Hyperbolic Geometry of Complex Matter from Nanoscale to Mesoscopic Scale

“…The hyperbolic space has recently been shown to influence critical phenomena [46]. The search for complex materials with zero or negative dielectric constant as been one of the road maps proposed for the amplification of the superconducting critical temperature to reach room temperature superconductivity [47][48][49][50][51][52][53]. The present experiments show a hyperbolic space in the mesoscale of cuprates but it could be present also in pressurized sulfur hydride superconductors [54,55], iron based superconductors [56] and diborides [57] which all show local lattice fluctuations.…”

On the frequency dependent negative dielectric constant behavior in Al/Co-doped (PVC+TCNQ)/p-Si structures

“…If the imaginary part is positive the effective terminal behavior is capacitive and if it is negative the effective terminal effect is inductive. [6][7][8][9][10][11] In recent years, some researchers have reported a negative capacitance (NC) [6][7][8][9][10][11][12][13] or negative dielectric constant (NDC) [14][15][16] in the forward bias C-V characteristics in some devices. The observation of NDC and NC are important because they imply that an increment of bias voltage produces a decrease in the charge on the electrodes.…”

Detection of the Meissner effect with a diamond magnetometer

“…The superconducting transitions observed to date are all below 135 K under normal atmospheric pressure and they are mostly associated with bulk systems. In recent years, the search for room-temperature superconductivity has been approached from several different angles [1], including searching for systems with negative dielectric functions [2], synthesizing crystals with specific phonon spectra [3], creating materials with a pore structure [4], and studying the superconducting state at interfaces in epitaxial heterostructures [5].…”