Optical characteristics of charge carrier transfer across interfaces between YBa2Cu3O6+δ and La0.7Ca0.3MnO3

Transition metal oxides undergo many different phase transitions when doped with charge carriers. Thanks to recent advances in the synthesis of metal-oxide heterostructures, doping can now be achieved through charge transfer across interfaces. This paper reports spectral ellipsometry measurements on multilayers of superconducting cuprates and ferromagnetic manganates and demonstrates that the optical spectra reveal fingerprints of interfacial charge transfer. Optical spectroscopy can thus serve as a nondestructive probe of the doping level at buried metal-oxide interfaces.