Magnetic field dependent evolution of band structure in La_(1-x)Ca_xMnO_3 (x = 0.18 and 0.30)

摘要

Probing of the evolution of electronic structure in magnetic field is a key issue for the design and realization of manganite-based devices. Here, the shift of the maximum (or minimum) position in unusual magnetoresistance (MR) versus V curves of the heterojunctions composed of La_(1-x)Ca_xMnO_3 (LCMO, x = 0.18 and 0.3) and 0.5 wt% Nb-doped SrTiO_3 (SNTO) was used to investigate the change of band gaps of LCMO with magnetic field. Negative and positive MRs which depend on temperature, bias current (or voltage), and Ca concentration observed in these heterojunctions are directly determined by the band structure at the LCMO-SNTO interface.