A5010825830- Physics of Superconductivity and Magnetism
- Quantum and electron transport phenomena
- Advanced Electrical Measurement Techniques
- Magnetic properties of thin films
- Magneto-Optical Properties and Applications
- Magnetic and transport properties of perovskites and related materials
- Iron-based superconductors research
- Electronic and Structural Properties of Oxides
- Superconductivity in MgB2 and Alloys
- Particle accelerators and beam dynamics
- Atomic and Subatomic Physics Research
- Advanced Condensed Matter Physics
- Semiconductor materials and devices
- Multiferroics and related materials
- ZnO doping and properties
- Superconducting Materials and Applications
- Surface and Thin Film Phenomena
- Spectroscopy and Laser Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Seismic Waves and Analysis
- HVDC Systems and Fault Protection
- Neural Networks and Reservoir Computing
- Metal and Thin Film Mechanics
- Diamond and Carbon-based Materials Research
- Advancements in Photolithography Techniques
University of California, Riverside
2016-2024
University of California, San Diego
2004-2018
Lawrence Berkeley National Laboratory
2008-2016
University of California, Berkeley
2007-2016
University of California, Los Angeles
2005
We report the creation of a multiferroic field effect device with ${\mathrm{BiFeO}}_{3}$ (BFO) (antiferromagnetic-ferroelectric) gate dielectric and ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ (LSMO) (ferromagnetic) conducting channel that exhibits direct, bipolar electrical control exchange bias. show bias is reversibly switched between two stable states opposite polarities upon ferroelectric poling BFO. No cooling, temperature cycling, or additional applied magnetic electric...
In this work, we demonstrate the ability to fabricate superconducting quantum interference devices (SQUIDs) by directly writing Josephson junctions into plane of YBa2Cu3O7−δ thin films with a focused helium ion beam. This technique allows for control barrier transport properties through single parameter, dose. SQUIDs written dose 4 × 1016 ions/cm2 had metallic that exhibited nearly ideal electrical characteristics at 50 K and flux noise 20 μΦ0/Hz 10 Hz. At higher irradiation doses,...
We report the fabrication of nanoscale wires and Josephson junctions in 25 nm thick YBa2Cu3O7–δ thin films with wire widths as narrow 50 nm. Our approach utilizes a finely focused gas field ion source from helium microscope to directly modify material on nanometer scale convert irradiated regions film into insulators. In this manner, remains intact no is milled or removed. Transport data show that electrical properties, critical current conductance, linearly lithographically defined width...
Direct write patterning of high-transition temperature (high-TC) superconducting oxide thin films with a focused helium ion beam is formidable approach for the scaling high-TC circuit feature sizes down to nanoscale. In this letter, we report using technique create sensitive micro quantum interference device (SQUID) magnetometer sensing area about 100 × μm2. The fabricated from single 35-nm thick YBa2Cu3O7-δ film. A flux concentrating pick-up loop directly coupled 10 nm 20 μm nano-slit...
Very large scale integration of Josephson junctions in a two-dimensional series−parallel array has been achieved by ion irradiating YBa2Cu3O7−δ film through slits nanofabricated mask created with electron beam lithography and reactive etching. The consisted 15820 high aspect ratio (20:1), 35 nm wide that restricted the irradiation below to form junctions. Characterizing each parallel segment k, containing 28 junctions, single critical current Ick we found standard deviation about 16%.
We have fabricated and tested two-dimensional arrays of YBa2Cu3O7−δ superconducting quantum interference devices. The contain over 36 000 nano Josephson junctions from ion irradiation through narrow slits in a resist-mask that was patterned with electron beam lithography reactive etching. Measurements current-biased magnetic field exhibit large voltage modulations as high 30 mV.
In superconductors, magnetic fields are quantized into discrete fluxons (flux quanta Φ0), made of microscopic circulating supercurrents. We introduce a multiterminal synapse network comprising disordered array superconducting loops with Josephson junctions. The can trap defining memory, while the junctions allow their movement between loops. Dynamics through such system complex reconfigurable energy landscape represents brain-like spiking information flow. this work, we experimentally...
We report the fabrication and measurement of quantum flux parametron logic from high-transition-temperature Josephson junctions operating at 25 K, above temperature liquid helium. The circuits are written directly into plane a single-layer thin film YBa2Cu3O7 using focused helium ion beam. A single-cell was constructed correct operation verified by an on-chip superconducting interference device for readout. three-cell shift register also fabricated tested three-phase clock cycle. estimate...
Irradiation of high-temperature superconductor YBa2Cu3O7 (YBCO) with high-energy He+ ions is known to cause structural changes in the YBCO film, decreasing critical temperature TC and finally leading a superconductor-to-insulator transition. This allows one pattern narrow insulating regions focused ion beam (FIB) thus fabricate nanoscale Josephson junctions on films. Moreover, such irradiation film. However, details how these occur devices produced by FIB remain unknown. Using nanofocus...
We have fabricated planar thin-film MgB2 Josephson junctions and 20-junction series arrays using 200-keV ion implantation electron-beam lithography. Resistively shunted junction I-V characteristics were observed in the temperature range of 34–38K. The ac effect was flat giant Shapiro steps suggest good uniformity with a small spread parameters. dependence critical current suggests that nature interface between superconductor normal region can be described soft boundary proximity coupling...
We have fabricated a series array of 280 superconducting quantum interference devices (SQUIDs) using YBa2Cu3O7−δ thin film ion damage Josephson junctions. The SQUID loop areas were tapered exponentially so that the response current-biased to magnetic field is single voltage spike at zero field. fitted current-voltage characteristics model in which we summed voltages across SQUIDs assuming resistively shunted junction with normal distribution critical currents. At 75 K standard deviation...
We have fabricated series-parallel (two-dimensional) arrays of incommensurate superconducting quantum interference devices (SQUIDs) using YBa2Cu3O7−δ thin film ion damage Josephson junctions. The initially consisted a grid junctions with 28 in parallel and 565 series, for total 15 255 SQUIDs. the direction were sequentially decreased by removing them photolithography milling to allow comparisons voltage–magnetic field (V–B) characteristics different dimensions area distributions. Comparisons...
In this work, we present nanoscale superconducting quantum interference devices (SQUIDs) with dimensions as small 10 nm from the high-transition-temperature superconductor YBa2Cu3O7−δ (YBCO). The SQUID features and Josephson junctions are directly written into a 35-nm thick YBCO film focused helium ion beam. We integrate these nano-SQUIDs nano-isolated inductively coupled control lines to demonstrate low power output driver capable of transimpedance conversion over very wide temperature range 4–50 K.
We report the fabrication and testing of arrays nanoscale superconducting quantum interference devices (SQUIDs) directly written into a thin film high-transition temperature superconductor YBa2Cu-3O7−δ with focused helium ion beam. compare three array configurations 400 nm by nanoSQUIDs connected in series parallel two-dimensional (2D) combination both. Our electrical transport measurements show that exhibit modulation voltages greater than 1 mV combining greatly enhances slope...
We have fabricated in-plane high-Tc Josephson junction pairs and series arrays using our established nanolithography ion damage process. Junctions in a pair showed nearly identical electrical properties. The ten-junction array exhibited current–voltage characteristics that can be described by the resistively shunted model at 78K. Flat giant Shapiro steps were observed both cases. believe ion-damaged superconducting is good candidate to form large numbers of junctions function above 77K for...
We have fabricated planar superconductor-normal metal-superconductor MgB2 Josephson junctions using TiB2 as the barrier material. On a bilayer film of MgB2∕TiB2 on SiC substrate, was locally removed to create gap ⩽50nm, separating into two electrodes. A coupling is established through across by proximity effect. The exhibit resistively shunted junction like current-voltage characteristics up 31K. An ac effect observed and behavior Shapiro steps are in good agreement with theoretical...
We investigate the temporal stability of YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O xmlns:xlink="http://www.w3.org/1999/xlink">7-δ</sub> Josephson junctions created by ion irradiation through a nanoscale implant mask fabricated using electron beam lithography and reactive etching. A comparison current-voltage characteristics measured for after fabrication eight years...
Focused helium ion beam material modification is ideally suited for the fabrication of YBa2Cu3O7-δ (YBCO) Josephson junctions and superconducting feature sizes down to nanoscale. We report measurement YBCO nano-slit SQUIDs study how scaling dimensions SQUID body electrodes influences electrical properties. Sixteen with different width length were fabricated from a single-layer 25-nm-thick film. The experimental results yield an estimation sheet inductance be ~4 pH/□ penetration depth ~180...
We investigated series arrays of closely spaced, planar long Josephson junctions for magnetic field transduction in Earth’s field, with a linear response and high dynamic range. The devices were fabricated from thin film high-temperature superconductor YBa2Cu3O7−δ (YBCO) films, using focused helium ion beam irradiation to create the barriers. Four arrays, each consisting several hundreds junctions, electrically tested. From fits current-voltage characteristics, we estimate standard deviation...
The interaction between two different materials can present novel phenomena that are quite from the physical properties observed when each material stands alone. Strong electronic correlations, such as magnetism and superconductivity, be produced result of enhanced Coulomb interactions electrons. Two-dimensional powerful candidates to search for because easiness arranging them modifying their accordingly. In this work, we report magnetic effects graphene, a prototypical non-magnetic...
Series arrays of closely spaced, planar long Josephson junctions were demonstrated to be transducers magnetic flux featuring high-dynamic range, wide-bandwidth, and the capability operate at cryogenic nitrogen temperatures. By tuning scaling geometry these devices, it is possible improve their sensitivity an applied field generate higher voltage responses. Moreover, devices feature linear responses allowing for potential unlocked operation. Herein, we study focusing effect in series...
Reproducible low resistance lumped element Josephson junction arrays are desired for many microwave applications. Using our established process of electron beam lithography and ion damage, we have fabricated demonstrated high quality YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// superconductor-normal superconductor-superconductor (SS'S) in-plane junctions. Single junctions multiple with as 50 in series been investigated. These close proximity offer several possible Current-voltage characteristics...