A5080737763- Electronic and Structural Properties of Oxides
- Semiconductor materials and devices
- Magnetic and transport properties of perovskites and related materials
- Ferroelectric and Negative Capacitance Devices
- Ferroelectric and Piezoelectric Materials
- Quantum and electron transport phenomena
- Acoustic Wave Resonator Technologies
- Diamond and Carbon-based Materials Research
- Advanced Condensed Matter Physics
- Graphene research and applications
- Molecular Junctions and Nanostructures
- Advanced Materials Characterization Techniques
- Photonic and Optical Devices
- Atomic and Subatomic Physics Research
- Carbon Nanotubes in Composites
- Cold Atom Physics and Bose-Einstein Condensates
- Physics of Superconductivity and Magnetism
- Advanced X-ray and CT Imaging
- Surface and Thin Film Phenomena
- Topological Materials and Phenomena
- Advanced Memory and Neural Computing
- Terahertz technology and applications
- Force Microscopy Techniques and Applications
- Mechanical and Optical Resonators
- Gyrotron and Vacuum Electronics Research
University of Pittsburgh
2016-2025
Pittsburgh Quantum Institute
2015-2024
Daresbury Laboratory
1994
Recent advances in creating complex oxide heterostructures, interfaces formed between two different transition metal oxides, have heralded a new era of materials and physics research, enabling uniquely diverse set coexisting physical properties to be combined with an ever- increasing degree experimental control. Already, these systems exhibited such varied phenomena as superconductivity, magnetism, ferroelasticity, all which are gate-tunable, demonstrating their promise for fundamental...
Complex-oxide interfaces host a diversity of phenomena not present in traditional semiconductor heterostructures. Despite intense interest, many basic questions remain about the mechanisms that give rise to interfacial conductivity and role surface chemistry dictating these properties. Here we demonstrate fully reversible >4 order magnitude conductance change at LaAlO3/SrTiO3 (LAO/STO) interfaces, regulated by LAO protonation. Nominally conductive are rendered insulating solvent immersion,...
SrTiO3-based heterointerfaces support quasi-two-dimensional (2D) electron systems that are analogous to III–V semiconductor heterostructures, but also possess superconducting, magnetic, spintronic, ferroelectric, and ferroelastic degrees of freedom. Despite these rich properties, the relatively low mobilities 2D complex-oxide interfaces appear preclude ballistic transport in 1D. Here we show LaAlO3/SrTiO3 interface can quantized electrons (nonsuperconducting) pairs within quasi-1D structures...
An unusual conductance sequence Effects of correlations between electrons are enhanced in systems reduced dimensions. The two-dimensional interface two oxide materials, lanthanum aluminate (LaAlO 3 ) and strontium titanate (SrTiO ), exhibits magnetism superconductivity. In even lower-dimensional fabricated similar heterostructures, can pair without going superconducting. Briggeman et al. have now observed another exotic effect LaAlO /SrTiO waveguides: At certain magnetic fields, the these...
Quantum materials (QMs) with strong correlation and nontrivial topology are indispensable to next-generation information computing technologies. Exploitation of topological band structure is an ideal starting point realize correlated QMs. Here, we report that strain-induced symmetry modification in oxide SrNbO3 thin films creates emerging structure. Dirac electrons strained reveal ultrahigh mobility (μmax ≈ 100,000 cm2/Vs), exceptionally small effective mass (m* ~ 0.04me), nonzero Berry...
The origin and function of chirality in DNA, proteins, other building blocks life represent a central question biology. Observations spin polarization magnetization associated with electron transport through chiral molecules, known collectively as the induced selectivity (CISS) effect, suggest that improves transfer by inhibiting backscattering. Meanwhile, role coherence within nanowires is believed to be important but challenging investigate experimentally. Using reconfigurable nanoscale...
The discovery of two-dimensional superconductivity in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>LaAlO</a:mi></a:mrow><a:mn>3</a:mn></a:msub><a:mo stretchy="false">/</a:mo><a:msub><a:mrow><a:mi>KTaO</a:mi></a:mrow><a:mn>3</a:mn></a:msub></a:mrow></a:math> (111) and (110) interfaces has raised significant interest this system. In paper, we report the first successful fabrication a direct current superconducting quantum interference...
We examine superconductivity in ${\mathrm{LaAlO}}_{3}/{\mathrm{SrTiO}}_{3}$ channels with widths that transition from the 1D to 2D regime. The superconducting critical current is independent of channel width and increases approximately linearly number parallel channels. Signatures electron pairing outside regime are also found be width. Collectively, these results indicate exists at boundary absent within interior region intrinsic nature interface imposes strong physical constraints on...
Nanoscale control of the metal-insulator transition at interface between LaAlO(3) and SrTiO(3) provides a pathway for reconfigurable, oxide-based nanoelectronics. Four-terminal transport measurements LaAlO(3)/SrTiO(3) nanowires room temperature (T = 300 K) reveal an equivalent 2D Hall mobility greatly surpassing that bulk approaching n-type Si comparable dimensions. This large enhancement is relevant room-temperature device applications.
High-mobility complex-oxide heterostructures and nanostructures offer new opportunities for extending the paradigm of quantum transport beyond realm traditional III-V or carbon-based materials. Recent investigations with LaAlO3/SrTiO3-based dots reveal existence a strongly correlated phase in which electrons form spin-singlet pairs without becoming superconducting. Here, we report evidence micrometer-scale ballistic electron quasi-1D LaAlO3/SrTiO3 nanowire cavities. In paired phase,...
Terahertz (0.1-30 THz) radiation reveals a wealth of information that is relevant for material, biological, and medical sciences with applications span chemical sensing, high-speed electronics, coherent control semiconductor quantum bits. To date, there have been no methods capable controlling terahertz (THz) at molecular scales. Here we report both generation detection broadband field from 10 nm scale oxide nanojunctions. Frequency components ultrafast optical are mixed these nanojunctions,...
The LaAlO${}_{3}$/SrTiO${}_{3}$ interface is already known to have interesting properties such as superconductivity and magnetism. Now nanoscale charge-transport networks created at the show extraordinary evidences of violation Ohm's law.
The interface between the two complex oxides LaAlO3 and SrTiO3 has remarkable properties that can be locally reconfigured conducting insulating states using a conductive atomic force microscope. Prior investigations of sketched quantum dot devices revealed phase in which electrons form pairs, implying strongly attractive electron-electron interaction. Here, we show these with strong interactions exhibit gate-tunable transition from pair-tunneling regime to single-electron (Andreev bound...
Freestanding membranes of electronically reconfigurable complex oxide heterostructure are demonstrated.
We report superconductivity in quasi-1D nanostructures created at the LaAlO3/SrTiO3 interface. Nanostructures having line widths w~10 nm are formed from parent two-dimensional electron liquid using conductive atomic force microscope lithography. Nanowire cross-sections small compared to superconducting coherence length (w<<xi~100 nm), placing them regime. Broad transitions with temperature and finite resistances state well below Tc~200 mK observed. V-I curves show switching between normal...
The interface between LaAlO3 and TiO2-terminated SrTiO3 can be switched metastable conductive insulating states using a atomic force microscope probe. Determination of the nanoscale dimensions has previously required destructive readout (e.g., local restoration an state). Here it is shown that high-resolution non-destructive imaging nanostructures achieved specific piezoresponse microscopy (PFM) technique. Images features are with feature sizes as small 30 nm. measured nanowire width from...
The widely reported magnetoresistance oscillations in LaAlO_{3}/SrTiO_{3} heterostructures have invariably been attributed to the Shubnikov-de Haas (SdH) effect, despite a pronounced inconsistency with low-field Hall resistance measurements. Here we report SdH-like quasi-1D electron waveguides created at interface by conductive atomic force microscopy lithography. These can be directly magnetic depopulation of magnetoelectric subbands. Our results suggest that SdH 2D SrTiO_{3}-based systems...
We report the development and characterization of graphene/LaAlO3/SrTiO3 heterostructures. Complex-oxide heterostructures are created by pulsed laser deposition integrated with graphene using both mechanical exfoliation transfer from chemical-vapor on ultraflat copper substrates. Nanoscale control metal-insulator transition at LaAlO3/SrTiO3 interface, achieved conductive atomic force microscope lithography, is demonstrated to be possible through layer. LaAlO3/SrTiO3-based electric field...
Complex-oxide heterostructures exhibit rich physical behavior such as emergent conductivity, superconductivity, and magnetism that are intriguing for scientific reasons well potential technological applications. It was recently discovered in-plane at the LaAlO3/SrTiO3 (LAO/STO) interface can be electronically controlled room temperature. Here, we employ magnetic force microscopy to investigate ferromagnetism LAO/STO with LAO thickness t varied from 4 unit cell (u.c.) 40 u.c. Magnetic...
Recent reports of superconductivity at KTaO3 (KTO) (110) and (111) interfaces have sparked intense interest due to the relatively high critical temperature as well other properties that distinguish this system from more extensively studied SrTiO3 (STO)-based heterostructures. Here, we report reconfigurable creation conducting structures intrinsically insulating LaAlO3/KTO(110) interfaces. Devices are created using two distinct methods previously developed for STO-based heterostructures: (1)...