Single-Electron Mediated Charge, Spin and Lattice Interactions in Oxide Nanostructures

University Of Pittsburgh, Pittsburgh PA

Investigators

Abstract

NON-TECHNICAL DESCRIPTION This research project will help provide physical understanding of a new oxide-based system capable of information storage and sensing at scales approaching the distance between atoms. Using a technique analogous to the perennial toy "etch-a-sketch", devices that operate with single electrons are being created. These devices store information at very high densities, and they are also predicted to be ultrasensitive sensors of both force and charge. The combined sensitivity, once understood properly, can be used to develop new types of devices and technologies. Aligned with the research goals are mentoring strategies for helping undergraduates learn advanced (but essential) subjects such as quantum mechanics. Mentoring strategies for underrepresented groups are also being pursued for both undergraduate and graduate students. TECHNICAL DETAILS This research project will identify and develop novel couplings between electron charge, spin, and nanomechanical degrees of freedom in oxide nanostructures. The research centers on a recently developed ferroelectric sketch-based single-electron transistor ("SketchSET"). Resonant tunneling into the SketchSET is modified by the ferroelectric polarization in SrTiO3, enabling an ultrasensitive electronic readout of the ferroelectric polarization (or strain) state. Initial experiments are further characterizing the SketchSET devices, and helping to define the relationship between writing parameters, charging energies, and tunnel barriers. The two-dimensional confining potential V(x,y) that forms the SketchSET are being mapped using a cryogenic atomic force microscope (AFM). Nanomechanical coupling is also being investigated using the piezoelectric and inverse-piezoelectric effects. Subsequent experiments couple a nanoscale mechanical object (e.g., C60 molecule or nanocrystalline quantum dot) placed atop the SketchSET and investigate coupling to phonon modes through inelastic tunneling experiments. Spintronic effects are being investigated at low temperature and high magnetic fields (50 mK/9T), with the purpose of investigating spin relaxation times and gauging the applicability of these systems for spin-based quantum information platforms. The Kondo regime for SketchSETs are being investigated, with a longer-term goal of creating artificial networks of localized and delocalized spin systems. Graduate students are receiving broad-based training in advanced techniques including sample processing, scanning probe microscopy and low-temperature magneto-transport.