Abstract
We have studied the transport properties of LaTiO3/SrTiO3 (LTO/STO) heterostructures. In spite of 2D growth observed in reflection high energy electron diffraction, transmission electron microscopy images revealed that the samples tend to amorphize. Still, we observe that the structures are conducting, and some of them exhibit high conductance and/or superconductivity. We established that conductivity arises mainly on the STO side of the interface, and shows all the signs of the two-dimensional electron gas usually observed at interfaces between STO and LTO or LaAlO3, including the presence of two electron bands and tunability with a gate voltage. Analysis of magnetoresistance (MR) and superconductivity indicates the presence of spatial fluctuations of the electronic properties in our samples. That can explain the observed quasilinear out-of-plane MR, as well as various features of the in-plane MR and the observed superconductivity.
Highlights
We have studied the transport properties of LaTiO3/SrTiO3 (LTO/STO) heterostructures
In spite of 2D growth observed in reflection high energy electron diffraction, transmission electron microscopy images revealed that the samples tend to amorphize
We have studied LTO/STO interfaces grown by pulsed laser deposition (PLD), and found that in spite of layer-by-layer growth signatures, the LTO layer tends to amorphize
Summary
Since the discovery of conductivity [1] at the interface between the two nonmagnetic band insulators LaAlO3 (LAO) and SrTiO3 (STO), oxide interfaces have been under intense investigation. We argue that the possible origin of these phenomena is the non-uniform distribution of oxygen vacancies on the STO surface due to the uncontrolled oxidation process in the LTO layer, which leads to spatial inhomogeneities This inhomogeneity is clearly seen in the superconducting state, but not discernible in the normal state, which is an important part of the message. Notwithstanding the observation of RHEED oscillations, results of scanning transmission electron microscopy (STEM) reveal that the LTO layer in our samples is amorphous (see inset in figure 1(e)) This is probably due to a relatively high oxygen growth pressure, which, as mentioned, leads to overoxidation and defective or even amorphous films [17,18,19]. Of the LTO layer was checked by using additional gold wires, which were glued by silver paint to the surface of the sample, and resistance was measured by a source meter with an applied current of 1 μA in a two-probe geometry
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
