Metal-to-insulator transition in Ruddlesden-Popper-type Srn+1VnO3n+1 (n = 1, 2) epitaxial thin films as a function of strain and VO2 stacking layer number

Abstract

A series of Ruddlesden-Popper-type Srn+1VnO3n+1 (n = 1, 2) (001) epitaxial thin films was grown on LaAlO3 and LaSrGaO4 substrates with tensile and compressive epitaxial strains, respectively. The decrease in VO2 stacking layer number n and the increase in the interlayer distance between the (VO2)n layers resulted in metal-to-insulator transition. The sheet conductance of a single (VO2)n layer in Srn+1VnO3n+1 (n = 1, 2) was close to the well-known Ioffe–Regel limit, which suggests their two-dimensional electrical conduction. From resistivity and magnetoconductance measurements, it is found that renormalized electron–electron interaction and/or the Kondo effect were enhanced with the decrease in n, and possible quantum interference effects like weak localization were induced with the increase in the interlayer distance.