0000000000660802

AUTHOR

J.a.a.j. Perenboom

showing 2 related works from this author

Role of excitons in double Raman resonances in GaAs quantum wells

1996

Raman scattering by longitudinal-optical phonons has been measured in GaAs-AlAs multiple quantum wells at high magnetic fields. Doubly resonant scattering processes are observed at photon energies corresponding to magneto-excitons with different principal quantum numbers for the incoming and outgoing channels. The existence of these initially forbidden scattering processes, their resonance energies, and their relative intensities are correctly reproduced by our theoretical description. The model takes into account the excitonic nature of the intermediate states, as well as scattering processes involving a nonzero in-plane phonon wave vector, which is required to allow inter-Landau level sca…

PhysicsPhonon scatteringCondensed matter physicsCondensed Matter::OtherScatteringScattering lengthCorrelated Electron Systems / High Field Magnet Laboratory (HFML)02 engineering and technologyCondensed Matter::Mesoscopic Systems and Quantum Hall Effect021001 nanoscience & nanotechnology01 natural sciencesScattering amplitudeCondensed Matter::Materials Sciencesymbols.namesakeX-ray Raman scattering0103 physical sciencesPrincipal quantum numbersymbolsScattering theoryAtomic physics010306 general physics0210 nano-technologyGeneralLiterature_REFERENCE(e.g.dictionariesencyclopediasglossaries)Raman scatteringPhysical Review B
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Charge-carrier density collapse in and epitaxial thin films

2000

We measured the temperature dependence of the linear high field pH of La0.67Ca0.33MnO3 Tc = 232K) and La0.67Sr0.33MnO3 Tc = 345K) thin films in the temperature range from 4 K up to 360 K in magnetic fields up to 20 T. At low temperatures we find a charge-carrier density of 1.3 and 1.4 holes per unit cell for the Ca- and Sr-doped compound, respectively. In this temperature range electron-magnon scattering contributes to the longitudinal resistivity. At the ferromagnetic transition temperature Tc a dramatic drop in the number of charge-carriers n down to 0.6 holes per unit cell, accompanied by an increase in unit cell volume, is observed. Corrections of the Hall data due to a non saturated ma…

Materials scienceCondensed matter physicsTransition temperatureAtmospheric temperature rangeCondensed Matter PhysicsMagnetic hysteresisElectronic Optical and Magnetic MaterialsCondensed Matter::Materials ScienceMagnetizationFerromagnetismElectrical resistivity and conductivityHall effectCondensed Matter::Strongly Correlated ElectronsCharge carrierThe European Physical Journal B
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