Paper TF+AS+EM+NS+SS-ThM5
Metal-Insulator Transition Induced in SrVO₃ Thin Films

Thursday, October 31, 2013, 9:20 am, Room 104 A

Metal-insulator transition (MIT) in strongly correlated oxides has been an intriguing topic of condensed matter physics over many decades. SrVO₃ (SVO) with a 3d¹ electronic configuration for vanadium is a typical strongly correlated system for studying MIT. High quality epitaxial SVO thin films of various thicknesses were grown on (001)-oriented LSAT single crystal substrates by using a novel pulsed electron-beam deposition (PED) technique. Thick SVO films (~25 nm) exhibited metallic behavior with the electrical resistivity following the T² law that corresponds to a Fermi liquid system, the resistance ratio R(300K)/R(2K) was ~1.6. We observed a temperature driven MIT in SVO films with thicknesses below 6 nm. The emergence of this MIT can be attributed to the reduction in the effective bandwidth due to a crossover from a three-dimensional metal to a two-dimensional insulator. We also synthesized SrTi_1-xV_xO₃ (0 ≤ x ≤ 1) thin films with thicknesses of ~15 nm to study the chemical doping of Ti⁴⁺ ions in the SVO system. The films with high vanadium content (x > 0.7) were metallic following the T² law, and the films with low vanadium content (x < 0.7) were semiconducting following the variable range hopping mechanism. The x = 0.7 film showed a temperature driven MIT at ~100K. The observed MIT induced by the substitution of Ti⁴⁺ ions for V⁴⁺ ions could be interpreted by the induced Anderson localization that trapped the electrons below a mobility edge.