Showing papers on "Mott transition published in 1982"
TL;DR: In this article, a generalized RPA approach was proposed to account for the Mott transition, and some preliminary very rough numerical estimates were given for the low-density limit of the spin degrees of freedom.
Abstract: We first generalize the approach of the previous paper by including spin degrees of freedom. We classify the various spin states and we discuss the effect of interband exchange interactions. We then introduce screening, in the framework of a generalized RPA which incorporates Bose condensation of bound electron-hole pairs. We discuss in detail the low density limit : screening corrections do not change the sign of the compressibility, which remains positive, in contrast to previous estimates. We show that such RPA corrections reduce to an approximate form of the Van der Waals attraction between excitons. Viewing this RPA approach as an interpolation procedure at intermediate densities, we propose several interpolation schemes that should account for the Mott transition, and we give some preliminary very rough numerical estimates. Finally, we discuss the effect of band degeneracy on the ground state : different degeneracies in the two bands should lead to a normal plasma at high density while at low densities bound excitons « Bose condense », with a breakdown of their internal symmetry; we expect a first order transition with a liquid-gas phase separation.
89 citations
TL;DR: In this paper, a Rydberg atom gas quickly evolves into a plasma above a threshold density, which is attributed to collisions between the two types of atoms occurring faster than the medium expansion.
Abstract: A Rydberg atom gas quickly evolves into a plasma above a threshold density. The process is attributed to Rydberg-Rydberg and Rydberg-electron collisions occurring faster than the medium expansion. Observations are found in good agreement with a simple rate equation model. This effect is different from a Mott transition. Conditions for the occurrence of this latter effect in a Rydberg atom gas are briefly discussed.
61 citations
TL;DR: The phase transformations in the 4d transition metal yttrium (Y) and the 3D transition metal scandium (Sc) have been studied under pressure up to 45 GPa by energy dispersive X-ray diffraction as discussed by the authors.
26 citations
24 citations
TL;DR: The transition between free excitons and an electron-hole plasma was described for the first time by a theory based on full random-phase-approximation (RPA) screening in the plasma as discussed by the authors.
Abstract: The transition between free excitons and an electron-hole plasma is described for the first time by a theory based on full random-phase-approximation (RPA) screening in the plasma. The onset of exciton binding predicted is in excellent agreement with experimental data attributed to exciton dissociation in Si. It is suggested that the many-body electron-hole interaction may be well described by static RPA screening near the Mott transition.
16 citations
TL;DR: In this article, an exciton-plasma Mott transition in the photo-excited semiconductor was attributed to the onset of an excitation-plasmas Mott-transition in the semiconductor.
1 citations
01 Jan 1982
TL;DR: In this paper, the authors present experimental results of a time-resolved investigation of pure CuCl crystals, in which extremely high free carrier densities (n > 1020cm−3) are optically injected.
Abstract: We present experimental results of a time-resolved investigation of pure CuCl crystals, in which extremely high free carrier densities (n > 1020cm−3) are optically injected. Highly excited CuCl crystals have been extensively studied before [1], using nanosecond or subnanosecond optical pulses. However, the density of generated electron-hole pairs was limited so far by the onset of irreversible sample damage to values n < 1020cm−3. By using optical pulses of subpicosecond duration, it is possible to extend the range of carrier densities beyond the Mott dissociation limit [2]. Accordingly, a transition in the excited state of the system occurs, from an insulating phase of excitonic particles to a conducting phase consisting of a superdense plasma. Although the formation of an electron-hole plasma has been observed in several direct gap semiconductors, most notably GaAs [3], a dynamical study of the Mott transition in these materials has proved difficult, since the effective temperature of the plasma is comparable with the exciton binding energy. In CuCl, Ex = 0.2 eV so that the criterion Ex/kT ≫ 1 should be more easily satisfied. Interest in the dynamics of superdense plasmas in direct gap semiconductors has been recently revived, as it may lead to picosecond laser action with broadband tunability [4], and also for its implication in the behavior of fast bistable optical devices [5].
1 citations
1 citations
01 Jan 1982
TL;DR: In this article, a self-consistent theory of the electronic and atomic structure of binary liquid alloys was developed, where calculated liquid pair correlation functions were incorporated into a tight binding model.
Abstract: By incorporating calculated liquid pair correlation functions into a tight binding model for the electronic structure of binary liquid alloys, we have developed a self consistent theory of the electronic and atomic structure of liquid alloys. Model calculations for the gold-alkali systems show the existence of a gap in the density of states if the ratio of the electronegativity -difference to the mean overlap integral exceeds a certain value.