Extraordinary alternating metal-insulator transitions in CaRuO3 ultrathin films at integer multiples of 25 Å of thickness

Enhancement of Extraordinary Size Effect on CaRuO3 Ultrathin Films

“…Thus, it was proposed that CRO ultrathin films exhibited a high electrical resistivity approach applicable to the Mott insulator phase in Mott–Hubbard model. [ 3 ]…”

“…The ultraviolet photoemission spectroscopy measured while etching showed that the surface (≈1 nm) was oxidized and insulated. [ 3 ] The oxide layer led to errors in this study which examined the scaling dependence on the order of angstrom. Therefore, the insulating barrier CaF 2 was deposited in situ at low temperatures to protect the surface of the CRO ultrathin films from atmospheric contamination.…”

“…Thus, this study proposed a mechanism of the Mott-Peierls transition owing to the anisotropy of the size effect and the nesting property in the Fermi surface. [3,[33][34][35][36][37] The metallic state of the extraordinary size effect, which is the minimum value of electrical resistivity, exhibits a similar electrical resistivity as the bulk CRO. However, the maximum resistivity at 85 Å thickness differed from that at 35 Å by eight digits at 4.2 K. Although significant differences in scaling insulation have been observed, the enhancement requirements remain unclear.…”

“…Thus, this study proposed a mechanism of the Mott–Peierls transition owing to the anisotropy of the size effect and the nesting property in the Fermi surface. [ 3,33–37 ]…”

“…films. [1][2][3] Size effects originating from quantum wells is a unique phenomenon observed at artificial low dimensions [4][5][6][7][8][9] in films with thicknesses of the order of de Broglie wavelengths, which corresponds to the Fermi wave length l F in crystals. For example, the period of quantum size effect is ≈400 Å in the semimetallic bismuth, and approximately angstrom in monoatomic metals such as lead and palladium.…”