טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentOleg Prus
SubjectAn Experimental Study of the Thermodynamics of Strongly
Correlated Two-Dimensional Fermions
DepartmentDepartment of Physics
Supervisors Full Professor Sivan Uri
Professor Reznikov Michael


Abstract

The aim of this work is to investigate the role of Coulomb interactions in the thermodynamic properties of two dimensional electron and hole gases . Holes in GaAs/AlGaAs heterostructures and electrons in Si Metal-Oxide-Semiconductor structures were chosen for the experiments. The common property of these two dimensional fermion gases is the strong Coulomb interaction between particles, characterized by the ratio  between the potential energy, associated with the Coulomb interactions, and the particles kinetic energy. This ratio varied in the experiments described here between 1 and 10.

Compressibility measurements of  two dimensional hole gases (2DHG) in GaAs/AlGaAs heterostructures were carried out by the three plate capacitor method over a wide temperature range, . The results show a large negative, and almost temperature independent interaction contribution to the inverse compressibility. The zero temperature STLS numerical algorithm was extended to finite temperatures and aaplied to calculate the inverse compressibility as a function of the carrier density and temperature. A remarkable agreement between the experiments and the calculations was found.

The central part of this thesis concerns the magnetic properties of 2DEG by a novel direct method for measuring the derivative of  the magnetization with respect to density . The method enabled us to obtain the magnetization by integrating  with respect to density. We found  full electron polarization at sufficiently large fields. No ferromagnetic instability was found in the whole parameter space studied in the experiment ( and ).  The magnetic susceptibility was found to be substantially enhanced by interactions.