טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentNitzav Yuval
SubjectThe Sign Reversal of the Hall Resistance in the Mixed State
of the Bi2212 High Tc Superconductors
DepartmentDepartment of Physics
Supervisor Professor Amit Kanigel


Abstract

The Hall anomaly in the High temperature superconductors (HTSC) is an open question for more than 30 years. There are many models that try to explain this phenomenon, some leaning on different known phases of the cuprates phase diagram and some are not.

In order to understand this phenomenon better, in this work we have decoupled the critical temperatures and doping of Bi2212 samples by introducing Zn atoms to the crystal. This lowers the critical temperature without changing the doping level of the sample.

We have produced both pristine and Zn substituted Bi2212 samples in a wide range of critical temperatures and doping levels. These samples were measured for Hall conductivity in a range of temperatures and magnetic fields.

We have found that the sign reversal line in the B-T plane is determined by the critical temperature and indifferent to the doping level of the sample.

We have also calculated the Hall deviation from the Bardeen Stephen model and introduced a phenomenological function for the behavior of the Hall deviation as a function of magnetic field, which captures the deviation size of the sample for a given temperature.

The deviation size is found to be indifferent to doping levels and is ordered by the critical temperature of the sample.

Thus, we conclude that the Hall anomaly is a superconductivity related phenomenon only.