Temperature-Dependent Pseudogaps in Colossal Magnetoresistive Oxides

TL;DR

This study investigates how pseudogaps in colossal magnetoresistive oxides vary with temperature and sample dimensionality, revealing their connection to transport properties and ruling out extrinsic effects.

Contribution

It provides direct electronic structure measurements showing the temperature and dimensionality dependence of pseudogaps in CMR oxides, clarifying their intrinsic nature.

Findings

Pseudogap presence at the Fermi energy suppresses spectral function.

Pseudogap magnitude varies with layer number and temperature.

Pseudogap changes correlate with transport and magnetic transition.

Abstract

Direct electronic structure measurements of a variety of the colossal magnetoresistive oxides show the presence of a pseudogap at the Fermi energy E_F which drastically suppresses the electron spectral function at E_F. The pseudogap is a strong function of the layer number of the samples (sample dimensionality) and is strongly temperature dependent, with the changes beginning at the ferromagnetic transition temperature T_c. These trends are consistent with the major transport trends of the CMR oxides, implying a direct relationship between the pseudogap and transport, including the "colossal" conductivity changes which occur across T_c. The k-dependence of the temperature-dependent effects indicate that the pseudogap observed in these compounds is not due to the extrinsic effects proposed by Joynt.