Evolution of charge carriers for transport in electron-doped cuprate superconductor La_(1.89)Ce_(0.11)CuO_4 thin films

摘要

To reveal the evolution of charge carriers to the transport in La_(1.89)Ce_(0.11)CuO_4, we carefully measured the temperature and magnetic-field dependences of the Hall resistivity (ρ_(xy)) and longitudinal resistivity (ρ_(xx)). Two sign reversals of the Hall resistivity are observed in the normal state. In addition, the ρ_(xy) and ρ_(xx) show B~2 dependence in the temperature region of 40-50 K, similar to the behavior of the compensated metal; that is, the effective concentrations of electrons (n_e~*) and holes (n_h~*) are nearly equal. The possible origin of the sign reversal is attributed to the competition between n_e~*_h~* and τ_e/τ_h (the relaxation time ratio of electrons to holes), and the change of cyclotron orbits induced by the magnetic field is also considered.