Measurements of the Fermi surface of SrTiO3: Nb

Structure and correlation effects in semiconductingSrTiO3

“…The elliptic bands, with an aspect ratio of about 2.4, represent cuts through the in-plane-oriented d yz and d zx ellipsoidal pockets. The elongation of the ellipsoids is much stronger than the findings of the Shubnikov-de Haas oscillations, 17,18 in which the crystals with small values of n͑ϳ5 ϫ 10 18 cm −3 ͒ are used. However, the strong elongation is in agreement with the theoretical band model ͑n =10 19 -10 20 cm −3 ͒.…”

“…3͒ suggest that the electron-phonon coupling might play an important role for the thermoelectricity in doped STO. While the conduction-band structure of the n-doped STO was previously extracted using the photoemission spectroscopy [19][20][21][22] as well as the magnetotransport, 17,18 the precise evaluation of the Fermi-surface shape, effective mass, and electron-phonon interaction from ARPES bandstructure measurements is unique to the present study. The present work is only possible because of the very high energy and momentum resolution of the experiments that also cover several Brillouin zones of STO.…”

“…The thermoelectricity is directly related to the effective mass, which has been measured by different experimental methods 5,17,18,32 and rarely compared with calculations. 6,33 Differences between our observed value of effective mass and the calculated values suggest the need for improved electronic-structure calculations and further investigation of STO with different doping.…”

“…While earlier transport 17,18 and angle-resolved photoemission spectroscopy ͑ARPES͒ ͑Refs. 19-22͒ measurements provided some information, important details such as the Fermi-surface size and band offsets are in disagreement with theory 15,16 and furthermore the effects of the structural change and electron correlation on the band structure have not been determined.…”

Superconductivity on a Charge Diet

“…Intriguingly, the superconducting ground state is restricted to a limited doping window [11][12][13][14]. Thanks to the remarkably high mobility of electrons, another consequence of the large dielectric constant [10], quantum oscillations are observable and have been reported both in the bulk [15,16] and in the twodimensional [17][18][19][20] samples.…”