Observation of semi-localized dispersive states in the strongly correlated electron-doped ferromagnet Eu${}_{1-x}$Gd${}_x$O

Abstract

Chemical substitution plays a key role in controlling the electronic and magnetic properties of complex materials. For instance, in EuO, carrier doping can induce a spin-polarized metallic state, colossal magnetoresistance, and significantly enhance the Curie temperature. Here, we employ a combination of molecular-beam epitaxy, angle-resolved photoemission spectroscopy, and an effective model calculation to investigate and understand how semi-localized states evolve in lightly electron doped Eu${}_{1-x}$Gd${}_x$O above the ferromagnetic Curie temperature. Our studies reveal a characteristic length scale for the spatial extent of the donor wavefunctions which remains constant as a function of doping, consistent with recent tunneling studies of doped EuO. Our work sheds light on the nature of the semiconductor-to-metal transition in Eu${}_{1-x}$Gd${}_x$O and should be generally applicable for doped complex oxides.

References in corpus (4)

• Unfolding first-principles band structures
• Epitaxial and layer-by-layer growth of EuO thin films on yttria-stabilized cubic zirconia (001) using MBE distillation
• Observation of momentum space semi-localization in Si-doped $\beta$-Ga${}_2$O${}_3$
• Temperature dependence of the electronic structure and Fermi-surface reconstruction of Eu(1-x)Gd(x)O through the ferromagnetic metal-insulator transition