Epitaxial growth and scanning tunneling microscopy of LiV2O4 thin films on SrTiO3(111).

LiV₂O₄ is a mixed-valent spinel oxide and one of a few transition-metal compounds to host a heavy fermion phase at low temperatures. Although numerous experimental studies have attempted to elucidate how its 3d electrons undergo giant mass renormalization, spectroscopic probes that may provide crucial hints, such as scanning tunneling microscopy (STM), remain to be applied. A prerequisite is atomically flat and pristine surfaces, which, in the case of LiV₂O₄, are difficult to obtain by the cleavage of small, three-dimensional crystals. We report the epitaxial growth of LiV₂O₄ thin films with bulklike properties on SrTiO₃(111) via pulsed laser deposition and stable STM imaging of the LiV₂O₄(111) surface. The as-grown films were transferred ex situ to a room-temperature STM, where subsequent annealing with optional sputtering in ultrahigh vacuum enabled compact islands with smooth surfaces and a hexagonal 1 × 1 atomic lattice to be resolved. Our STM measurements provide insights into the growth mechanisms of LiV₂O₄ on SrTiO₃(111) as well as demonstrate the feasibility of performing surface-sensitive measurements of this heavy fermion compound. [ABSTRACT FROM AUTHOR]