Abstract
http://link.aps.org/doi/10.1103/PhysRevB.85.121106 (2012) We report on a systematic study of the temperature-dependent Hall coefficient
and thermoelectric power in ultra-thin metallic LaNiO$_3$ films that reveal a
strain-induced, self-doping carrier transition that is inaccessible in the
bulk. As the film strain varies from compressive to tensile at fixed
composition and stoichiometry, the transport coefficients evolve in a manner
strikingly similar to those of bulk hole-doped superconducting cuprates with
varying doping level. Density functional calculations reveal that the
strain-induced changes in the transport properties are due to self-doping in
the low-energy electronic band structure. The results imply that thin-film
epitaxy can serve as a new means to achieve hole-doping in other (negative)
charge-transfer gap transition metal oxides without resorting to chemical
substitution.
