Showing papers on "Mott transition published in 1978"

Mott distortion of the electron-hole fluid phase diagram

Abstract: Spectroscopic measurements of the electron-hole fluid in Ge indicate that the liquid-gas phase diagram is distroted from that of simple fluids. This Mott distortion appears as a broadening of the top of the phase diagram with gas densities at least a factor of 3 lower than expected in the region near the Mott density. The precise shape of the phase boundary in the high-density gas remains uncertain because of inadequacies in our theoretical and experimental understanding of screening effects at finite temperatures. However, no first-order Mott transition separate from the liquid-gas transition is found to occur.

First-Order Mott Transition of the Exciton Gas in GaP

Abstract: The high-density electron-hole system in GaP is investigated. The luminescence spectra are discussed as function of the excitation level and temperature. The Mott transition of the exciton gas is observed and the conditions are found for the separation into two phases between 40 and 70 K. A low-density phase is an insulator: a high-density phase (np = 5 × 1018 cm−3) is a conductor. Nous etudions le systeme electron-trou a forte densite dans GaP. Les spectres de luminescence sont analyses en fonction du niveau d'excitation et de la temperature. Nous observons la transition de Mott du gaz d'excitons et realisons les conditions pour la separation en deux phases entre 40 et 70 K. Une phase de faible densite est isolante; l'autre de forte densite (np = 5 × 1018 cm−3) est conductrice.

On the Optical Criterion for the Mott Transition

Abstract: The Mott criterion for disappearance of bounded electron states (metal–non-metal transition) is generalized to higher excited states. The results are applied to the interpretation of the optical measurements in solid mercury-xenon mixtures at very low temperatures. Mott's Kriterium fur das Verschwinden gebundener Elektronenzustande (Metall-Nichtmetallubergang) wird verallgemeinert und ausgedehnt auf hohere angeregte Zustande. Die Ergebnisse werden fur die Interpretation optischer Messungen an festen Quecksilber-Xenon-Mischungen bei sehr tiefen Temperaturen benutzt.

Electron-hole plasma luminescence in GaP

Abstract: An experimental investigation of the luminescence of strongly excited “pure” GaP has been performed as function of input light intensity and temperature. Three distinct situations are observed. For T K , the spectrum consists of a band, due to the recombination of the electron-hole liquid (EHL), coexisting with an exciton-rich gas phase. At T ≳ 40 K , the EHL band is still apparent, but the gas has evolved into an electron-hole plasma (EHP). Finally, at T > 60 K , only the EHP recombination remains and exhibits a density dependent lineshape as expected. The density at which the metal-insulator Mott transition occurs is compared to the calculations using the Debye-Huckel criterion.

The phase diagram of a system with two order parameters. Mott transition and ferromagnetism

Abstract: The phase diagram of the extended Caron-Pratt model is constructed. Competing order parameters describe ferromagnetic and metal–insulator phase transitions. The possible phases, the incompatibility of the order parameters, and the existence of the tricritical point are determined. Das Phasendiagramm des erweiterten Caron-Pratt-Modells wird konstruiert. Konkurrierende Ordnungsparameter beschreiben ferromagnetische und Metall–Isolator-Ubergange. Die moglichen Phasen, die Inkompatibilitat der Ordnungsparameter und die Existenz des trikritischen Punktes werden bestimmt.