Homes scaling in ionic liquid gatedLa2CuO4+xthin films

Abstract

Finding more efficient ways of exploring the doping phase diagrams of high temperature superconductors as well as probing the fundamental properties of these materials are essential ingredients for driving the discovery of new materials. We use a doping technique involving gating with ionic liquids to systematically and continuously tune the Tc of superconducting La2CuO4+x thin films. We probe both the transport properties and the penetration depth of these samples and find that Homes scaling λ −2 ∝ σTc is obeyed, consistent with these materials being in the dirty limit. This result is independent of the precise mechanism for the gating process as all of the parameters of the scaling relationship are determined by direct measurements on the films.

Prospect of quantum anomalous Hall and quantum spin Hall effect in doped kagome lattice Mott insulators

“…In recent years a few alternative techniques have been very successful in doping Mott insulators like deposition of alkali ions [54] or gating the materials with ionic liquids [55,56]. For instance, it has recently become possible to tune the critical temperature of La 2 CuO 4+x thin films by gating the parent compound [57]. Following different doping routes may allow the realization of our predictions.…”

A selective control of volatile and non-volatile superconductivity in an insulating copper oxide via ionic liquid gating

“…Several possible effects, such as electrostatic charge modulation [15,16], oxygen removal [28,35], and H + ions injection [23,[36][37][38] may arise during the PGV process in the oxide system. Considering the fact that the thickness of the PCO thin film,~60 nm, is much larger than the Thomas-Fermi screening length (several nanometers), pure electrostatic field effect can only modulate the electronic property of the surface layers, and therefore cannot extend to the whole film and suppress the superconductivity of the bulk.…”

“…0 V is unlikely to cause an electron doping effect. In other words, the superconducting phase SC II arises from a novel and peculiar effect, which is different from the PGV-driven deoxygenation or proton injection in copper-and iron-based superconductors [28,29,35]. In order to further verify that the SC II phase appearing after a cycle of NGV is indeed non-volatile, we did the measurements on another non-superconducting sample S3.…”

“…SrCoO2.5, [18] YBa2Cu3O7-x, [27] and La2CuO4. [28] That is, oxygen ions are introduced into the samples. In order to get an explicit picture of the non-volatile superconductivity we observed, in-situ XRD measurements were performed on an insulating PCO thin film at room temperature (see the Experimental Section for details).…”

Determining the absolute value of magnetic penetration depth in small-sized superconducting films

“…For the reflection-type MI setup, it is easy to implement further manipulations on the film [26][27][28] because both coils are under the substrate and the top side of the film is free. However, it is difficult to achieve highprecision measurement of λ when using this configura-tion.…”