Electric field control of the LaAlO3/SrTiO3 interface ground state

Control of electronic conduction at an oxide heterointerface using surface polar adsorbates

“…However, remotely changing electronic states far from the adsorbed layer is possible, if these states are electrostatically coupled to the surface. Here we show that the surface adsorption of common solvents such as acetone, ethanol, and water can induce a large change in the conductivity at the buried interface between SrTiO 3 substrates and LaAlO 3 thin films [3][4][5][6][7][8] , and an adsorbate induced insulator to metal transition was observed when the thickness of LaAlO 3 , d LAO , is around 3 unit cells (uc). This phenomenon is observed only for polar solvents.…”

“…This issue is addressed in the present work. We have found that the exposure of LaAlO 3 /SrTiO 3 samples to a polar solvent can increase the sheet carrier density, n 2d , by more than 2×10 13 cm − 2 , representing a change of the same order as the total charge density typical in this system [5][6][7][8] . Compared with the strong perturbations associated with other surface processes, that is, the extremely strong local electric field produced by the conducting atomic force microscopy probes [10][11][12][13] , or the structural variation by introducing capping layers grown at high temperatures 14,15 , the changes associated with room-temperature treatment using these solvents would naively be expected to be small.…”

“…The intense interest in the LaAlO 3 /SrTiO 3 interface [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] has led to several recent experimental observations that suggest a close relationship between the interface and the LaAlO 3 surface. These include the use of conducting atomic force microscopy probes to toggle a metal insulator transition [10][11][12] through the writing of surface charge 12,13 , and the use of capping layers of SrTiO 3 (ref.…”

Probing Quantum Confinement and Electronic Structure at Polar Oxide Interfaces

“…a) Field‐effect modulation of sheet resistance ( R s ) as a function of T on a semilogarithmic scale of the LASTO:0.5/STO interface (bottom panel), in comparison with the LAO/STO interface (top panel, replotted from ref. 21). For LASTO:0.5/STO, the gate voltage varies from −400 to +325 V in steps of 25 V. b) Perpendicular (dots) and parallel (squares) critical fields ( H ⊥ ∗ , H ∥ ∗ ) as a function of temperature ( T ) for the as‐grown state (left panel) and for a state with V g = 300 V (right panel) for LASTO:0.5/STO.…”

“…Figure 2a shows the modulation of the superconducting transitions when the gate voltage ( V g ) is varied from −400 to +325 V, in comparison with the data of the LAO/STO interface 21. We observe that T c and the normal state resistance (see the Supporting Information for the R s vs V g plot) are effectively tuned; we note however that for the largest negative voltages, i.e., in the strongest depletion regime, the system remains metallic and superconducting and we do not attain the insulating state reported for standard LAO/STO interfaces (top panel in Figure 2a).…”