相关论文: Multilevel Tunnelling Systems and Fractal Clusteri…
The low-temperature quasi-universal behavior of amorphous solids has been attributed to the existence of spatially-localized tunneling defects found in the low-energy regions of the potential energy landscape. Computational models of…
Structural two level systems (TLSs) ubiquitous in amorphous solids are dramatically sensitive to thermal cycling to about $20$K and then back to low temperature, a process upon which the excitation energy of most TLSs is significantly…
The density of Two-level systems (TLS) controls the low-temperature thermal properties in glasses and has been found to be almost depleted in ultrastable glasses. While this depletion of TLS is thought to have a close relationship with the…
A generalized tunneling model of multicomponent insulating glasses is formulated, considering tunneling states to be paramagnetic centers of the electronic hole type. The expression for magnetic field dependent contribution into the free…
The low temperature acoustic properties of bulk metallic glasses measured over a broad range of frequencies rigorously test the predictions of the standard tunneling model. The strength of these experiments and their analyses is mainly…
The low temperature acoustic and thermal properties of amorphous, glassy materials are remarkably similar. All these properties are described theoretically with reasonable quantitative accuracy by assuming that the amorphous solid contains…
We propose a microscopic translationally invariant glass model which exhibits two level tunneling systems with a broad range of asymmetries and barrier heights in its glassy phase. Their distribution is qualitatively different from what is…
In non-equilibrium experiments on the glasses Mylar and BK7, we measured the excess dielectric response after the temporary application of a strong electric bias field at mK--temperatures. A model recently developed describes the observed…
The compound, Fe2TiO5 (FTO)is a well-known uniaxial anisotropic spin-glass insulator with two successive glassy freezing temperatures i.e. transverse (TTF= 9K) and longitudinal (TLF= 55 K). In this article, we present the results of…
The 1kHz real part $\chi'$ of the dielectric constant of a structural glass was measured at low temperature $T$ down to 14 mK. Reducing the sample thickness $h$ to 10 nm suppresses the usual minimum of $\chi'$ for measuring fields $E<.5 $…
We present new data on the nonequilibrium acoustic response of glasses to an applied dc electric field below 1K. When compared with the analogous dielectric response of the same material, the acoustic data show, within experimental…
The anomalous magnetic field dependence of dielectric properties of insulating glasses in the temperature interval $10mK<T<50mK$ is considered. In this temperature range, the dielectric permittivity is defined by the resonant contribution…
At low temperatures, glasses exhibit distinctive properties compared to crystalline solids. A notable example is the phonon echo, a phenomenon that motivated the two-level-system (TLS) model. This model has successfully explained many…
We report on numerical procedures for, and preliminary results on the search for, tunnelling centres in Lennard-Jones clusters, seen as simple model systems of glasses. Several of the double-well potentials identified are good candidates to…
After a strong electric bias field was applied to a glass sample at temperatures in the millikelvin range its AC-dielectric constant increases and then decays logarithmically with time. For the polyester glass mylar we have observed the…
Recent advances in on-surface chemistry, combined with scanning probe microscopy, have enabled the synthesis of correlated molecules on surfaces and the characterization of their chemical and electronic properties with unprecedented spatial…
The novel isotope and magnetic effects on two level system echoes in glasses observed by Nagel et al.(Phys.Rev.Lett. 92, 245511 (2004)) provide unique experimental insight into the nature of tunneling systems in amorphous solids. We show…
Via computer simulations of the standard binary Lennard-Jones glass former we have obtained in a systematic way a large set of close-by pairs of minima on the potential energy landscape, i.e. double-well potentials (DWP). We analyze this…
Recently, it has been discovered that in contrast to expectations the low-temperature dielectric properties of some multi-component glasses depend strongly on magnetic fields. In particular, the low-frequency dielectric susceptibility and…
For disordered Heisenberg systems with small single ion anisotropy, two spin glass transitions below the long range ordered phase transition temperature has been predicted theoretically for compositions close to the percolation threshold.…