טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentOren Neumann
SubjectCalculating the Hall Anomaly in the t-J Model DMRG
DepartmentDepartment of Physics
Supervisor Full Professor Auerbach Assa
Full Thesis textFull thesis text - English Version


Abstract

We study in this work the t-J model which is believed to to be a model able to describe the phenomenon of high-Tc superconductivity in cuprate materials, an effect that is yet to receive a full explanation. We use this model to simulate another phenomenon, the Hall anomaly, an effect where the Hall conductivity of high-Tc superconducting materials changes its sign when electron filling is increased before reaching half-filling. we also calculate the change in energy of the ground state in order to measure the appearance of pair binding. Since an exact calculation of the t-J model's ground state is too expensive for large systems, we turn to DMRG, a numerical method that approximates the ground state using states with a short entanglement length. The Hall conductivity is calculated using the method of charge pumping, where magnetic flux is adiabatically added passing through the hole of a 2D cylindrical system and causes a shift in the charge distribution. This shift in charge is known to be related to the Hall conductivity. Though our calculation shows large fluctuations in the sign of the Hall conductivity at large electron fillings, we argue that the change in this sign is correlated with the binding of electron pairs, which could help to understand this phenomenon.