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in creator/contributor: "Jia, Q."

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ALTERNATIVE MATERIALS FOR RAMP-EDGE SNS JUNCTIONS

We report on the processing optimization and fabrication of ramp-edge high-temperature superconducting junctions by using alternative materials for both superconductor electrodes and normal-metal barrier. By using Ag-doped YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} (Ag:YBCO) as electrodes and a cation-modified compound of (Pr{sub y}Gd{sub 0.6{minus}y})Ca{sub 0.4}Ba{sub 1.6}La{sub 0.4}Cu{sub 3}O{sub 7} (y = 0.4, 0.5, and 0.6) as a normal-metal barrier, high-temperature superconducting Josephson junctio… more

Date: June 1999

Creator: Jia, Q. & Fan, Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

AN INTEGRATED SOLID-STATE OPTICAL DEVICE WITH HIGH-SPEED SCANNING, VARIABLE FOCUSING, AND FREQUENCY-DOUBLING CAPABILITIES

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Date: August 1, 2001

Creator: JIA, Q.; GAHAGAN, K. T. & AL, ET

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

STM and x-ray diffraction temperature-dependent growth study of SrRuO{sub 3} PLD thin films

SrRuO{sub 3} (SRO) has recently found a number of applications in different fields, e.g. as a buffer layer for the growth of high temperature superconductor (HTS) YBa{sub 2}Cu{sub 3}O{sub 7-x} films and as a bottom electrode for ferroelectric or high dielectric constant thin film capacitors and nonvolatile data storage. The growth of high crystallinity SRO films with good structural and electrical properties is the prerequisite for each of these applications. In this paper we describe the affec… more

Date: December 31, 1996

Creator: Hawley, M. E.; Jia, Q. X. & Brown, G. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Substrate and growth related microstructural and magnetic properties in La{sub 0.67}Sr{sub 0.33}MnO{sub 3} thin films

Ambient observation of magnetic domain structures by magnetic force microscopy (MFM) in La{sub 0.67}Sr{sub 0.33}MnO{sub 3} films has not yet been clearly correlated with stresses induced by kinetic or thermodynamic growth processes or the compressive (LaAlO{sub 3}) or tensile (SrTiO{sub 3}) nature of the film-substrate lattice mismatch. Although domain-like magnetic structures have been seen in some as-grown films and related to substrate-induced stress and film thickness, no magnetic structure… more

Date: December 31, 1998

Creator: Hawley, M. E.; Brown, G. W.; Kwon, C. & Jia, Q.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Microstructures and electrical properties of SrRuO{sub 3} thin films on LaAlO{sub 3} substrates

Conductive SrRuO{sub 3} thin films have been deposited using pulsed laser deposition. Structure and microstructure of this system were studied using XRD, SEM, and scanning tunneling microscopy. Electrical properties of these films were measured. The film deposited at 250{degree}C is amorphous-like, showing semiconductor-like temperature dependence of electric conductivity. Film deposited at 425{degree}C is crystalline with very fine grain size (100 {approximately} 200{angstrom}), showing both m… more

Date: March 1, 1996

Creator: Chu, F; Mitchell, T.E.; Hawley, M; Landrum, G; Jia, Q.X. & Wu, X.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-temperature superconducting thin-film-based electronic devices

This the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project involved optimization of processing of Y123 and Tl-2212 thin films deposited on novel substrates for advanced electronic devices. The Y123 films are the basis for development of Josephson Junctions to be utilized in magnetic sensors. Microwave cavities based on the Tl-2212 films are the basis for subsequent applications as communication anten… more

Date: September 1, 1996

Creator: Wu, X.D; Finokoglu, A.; Hawley, M.; Jia, Q.; Mitchell, T.; Mueller, F. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Observation of spin-dependent tunneling and large magnetoresistance in La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3}/La{sub 0.7}Sr{sub 0.3}MnO{sub 3} ramp-edge junctions

The authors have fabricated ferromagnet-insulator-ferromagnet tunneling junctions using a ramp-edge geometry based on (La{sub 0.7}Sr{sub 0.3})MnO{sub 3} ferromagnetic electrodes and a SrTiO{sub 3} insulator. Pulsed laser deposition was used to deposit the multilayer thin films and the devices were patterned using photolithography and ion milling. As expected from the spin-dependent tunneling, the junction magnetoresistance is dependent on the relative orientation of the magnetization in the ele… more

Date: December 31, 1997

Creator: Kwon, C.; Jia, Q.X.; Fan, Y.; Hundley, M.F. & Reagor, D.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

DIELECTRIC PROPERTIES OF BA(0.6)SR(0.4)TiO(3) THIN FILMS WITH VARIOUS STRAIN STATES

We could systematically control the strain states of a Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} film by depositing a very thin Ba{sub 1{minus}x}Sr{sub x}TiO{sub 3} interlayer between the main layer of the Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} and a MgO(001) substrate. Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} films showed very strong dependence of dielectric properties on the strain states. The strain induced by the MgO substrate was relaxed faster than that induced by an interlayer.

Date: April 2001

Creator: Park, B. H.; Peterson, E. J.; Lee, J.; Zeng, X.; Si, W.; Xi, X. X. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Transport and magnetism correlations in thin-film ferromagnetic oxides

In order to determine the {Tc}-dependence of the colossal magnetoresistance (MR) exhibited by the ferromagnetic La{sub 0.7}M{sub 0.3}MnO{sub 3+{sigma}} (M = Ba, Ca, Sr) system, the authors examine the magnetic-field and temperature dependent resistivity and magnetization of a series of thin films that were grown via pulsed-laser deposition. The films had magnetic ordering temperatures (T{sub C}) ranging from 150 to 350 K; all samples displayed a large negative MR that is largest near {Tc}. The … more

Date: September 1, 1995

Creator: Hundley, M. F.; Neumeier, J. J.; Heffner, R. H.; Jia, Q. X.; Wu, X. D. & Thompson, J. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Ultra-sensitive sensors for weak electromagnetic fields using high-{Tc} SQUIDS for biomagnetism, NDE, and corrosion currents

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The research has directly contributed to a new DOE supported project, three patents (one granted and two submitted), and several potential opportunities for new program funding at the Laboratory. The authors report significant developments extending from basic understanding of and fabrication techniques for high critical-temperature (high-{Tc}) SQUI… more

Date: November 1, 1998

Creator: Kraus, R. H., Jr.; Flynn, E.R.; Espy, M.; Jia, Q.X.; Wu, X.D. & Reagor, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Development of N-layer materials for SNS junction and SQUID applications

Materials characteristics including water reactivity, oxygen loss, electromigration of oxide ions, and interfacial reactivity problems have plagued attempts to produce reliable and reproducible cuprate SNS superconductor junctions. In an effort to solve some of these formidable problems, new N-layer compounds from the family of R{sub 1{minus}x}Ca{sub x}Ba{sub 2{minus}y}La{sub y}Cu{sub 3{minus}z}M{sub z}O{sub 7{minus}{delta}} (R = Y, Gd and Pr; M = Co, Ni and Zn; 0 < x < 0.4; 0 < y < 0.4; 0 < z … more

Date: September 1, 1997

Creator: Zhou, J. P.; McDevitt, J. T. & Jia, Q.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Integration of electro-optic lenses and scanners on ferroelectric LiTaO{sub 3}

An integrated electro-optic lens/scanner device was fabricated on a ferroelectric LiTaO{sub 3} wafer. This was done using lithographically defined domain-inverted regions extending through the crystal thickness. A lens power of 0.233 cm{sup {minus}1}kV{sup {minus}1} and a scanner deflection of 12.68 mrad{sup {minus}1}kV{sup {minus}1} was observed. The authors also demonstrate an electro-optic lens stack collimator which collimates an input beam focused to a 5{micro}m waist diameter at {minus}2.… more

Date: March 13, 1999

Creator: Gopalan, V.; Gahagan, K. T.; Jia, Q. X.; Tobinson, J. M.; Mitchell, T. E.; Schlesinger, T. E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Interplay between electronic transport and magnetic order in ferromagnetic magnetic manganite thin films

The transition metal oxides La{sub 1{minus}x}A{sub x}MnO{sub 3} (A = Ba, Ca, or Sr) order ferromagnetically with Curie temperatures ranging from as low as 50 K to well above room temperature. Magnetic order in these compounds results in a concomitant metal-insulator transition. The feature displayed by the manganites that is most important technologically is the extremely large negative magnetoresistance that achieves its largest values near the magnetic ordering temperature. Qualitatively, thi… more

Date: May 1, 1997

Creator: Hundley, M. F.; Neumeier, J. J.; Heffner, R. H.; Jia, Q. X.; Wu, X. D. & Thompson, J. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Development of materials for high temperature superconductor Josephson junctions

We have conducted a systematic optimization of deposition parameters for fabrication of multilayered oxide films to be used in the development of high temperature superconducting SNS Functions. These films were deposited by off-axis sputtering using a custom fabricated multi-gun planar magnetron system. Each material and the various combinations of materials were optimized for epitaxial lattice match, crystal quality, film uniformity, electrical properties, and surface microstructure. In additi… more

Date: October 1, 1994

Creator: Houlton, R. J.; Reagor, D. W.; Hawley, M. E.; Springer, K. N.; Jia, Q. X.; Mombourquette, C. B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Observation of large low field magnetoresistance in ramp-edge tunneling junctions based on doped manganite ferromagnetic electrodes and a SrTiO{sub 3} insulator

The authors report the fabrication of ferromagnet-insulator-ferromagnet junction devices using a ramp-edge geometry based on (La{sub 0.7}Sr{sub 0.3})MnO{sub 3} ferromagnetic electrodes and a SrTiO{sub 3} insulator. The multilayer thin films were deposited using pulsed laser deposition and the devices were patterned using photolithography and ion milling. As expected from the spin-dependent tunneling, the junction magnetoresistance depends on the relative orientation of the magnetization in the … more

Date: July 1, 1998

Creator: Kwon, C.; Jia, Q. X.; Fan, Y.; Hundley, M. F.; Reagor, D. W.; Hawley, M. E. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Fabrication and characterization of high-speed integrated electro-optic lens and scanner devices

Uniaxial strain impact experiments have been performed to obtain shock compression and release response of a 0.22 g/cm{sup 3} polyurethane foam in a configuration where the foam impacts a thin target witness plate. Wave profiles from a suite of ten experiments have been obtained, where shock amplitudes range from 40 to 500 MPa. A traditional P-{alpha} porous material model generally captures the material response. A fully three-dimensional explicit representation of the heterogeneous foam struc… more

Date: February 1, 1999

Creator: Gahagan, K. T.; Gopalan, V.; Jia, Q. X.; Kawas, M. J.; Mitchell, T. E.; Robinson, J. M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Science and technology of reduced-dimensional magnetic materials

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). This work involved the synthesis of single crystal and thin film samples of magnetoresistive manganites (LaMnO{sub 3} doped with Ca and Sr) and the characterization of their electronic transport properties to understand the underlying physical mechanisms responsible for the colossal magnetoresistance (CMR) of these materials. The experimental program wa… more

Date: December 31, 1998

Creator: Heffner, R. H.; Bishop, A. R.; Hundley, M. F.; Jia, Q.; Neumeier, J. J.; Trugman, S. A. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

High-Tc Coated Conductors - Performance of Meter-Long YBCO/IBAD Flexible Tapes

One meter long tapes based on 50-100 {micro}m thick by 1 cm wide nickel alloy substrates have been coated in a continuous process with a textured yttria-stabilized zirconia layer by ion beam-assisted deposition, followed by a 1-2 {micro}m thick layer of YBCO by pulsed laser deposition. The best result to date is a tape with a critical current (I{sub c}) at 75 K of 96 A over an 87 cm measurement length. The overall critical current density and engineering current density are 1 MA/cm{sup 2} and 1… more

Date: September 13, 1998

Creator: Foltyn, S. R.; Arendt, P. N.; Dowden, P. C.; DePaula, R. F.; Groves, J. R.; Coulter, J. Y. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Growth and magnetic structure of La{sub 0.67}Sr{sub 0.33}MnO{sub 3} films

Growth of LaMnO{sub 3} films that exhibit colossal magnetoresistance (CMR) has concentrated heavily on Ca doped materials. However, since the 33% Sr doped films are ferromagnetic at room temperature, they are ideal candidates for dual growth-magnetic structure studies using scanned probe techniques. In this study, interest was focused on the relations between growth/processing parameters, film morphology, and electronic/magnetic properties. In addition, films were grown on both LaAlO{sub 3} (LA… more

Date: August 1, 1997

Creator: Brown, G. W.; Jia, Q. X.; Peterson, E. J.; Hristova, D. K.; Hundley, M. F.; Thompson, J. D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department