Effects of 1-MeV proton irradiation in Hg-based cuprate thin films

Gapud, A.A.; Liu, J.R.; Wu, Judy; Kang, W. N.; Kang, Byeongwon; Yun, Sang‐Ho; Chu, W. K.

doi:10.1103/physrevb.56.862

Cited by 14 publications

(4 citation statements)

References 34 publications

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“…In that regime, continuous columnar defects can be fabricated along ion tracks 8,9,11 in perfect accordance with a long-accepted "consensus" that a cylindrical APC is most effective for increasing J c . 7,14 Conversely, despite its industrial affinity, ion irradiation in the nuclear-stopping regime (<5 MeV), where ions are decelerated by elastic collisions, has lacked an extensive investigation in the context of in-field-J c enhancement, [15][16][17] based on an assumption that expected point-like defects 9,11 are not as effective as continuous ones.…”

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confidence: 97%

4-fold enhancement in the critical current density of YBa2Cu3O7 films by practical ion irradiation

Matsui

Ogiso

Yamasaki

et al. 2012

Applied Physics Letters

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We report an up-to-4-fold enhancement in the in-magnetic-field critical current density at 77 K of epitaxial YBa 2 Cu 3 O 7 films on CeO 2 -buffered SrTiO 3 substrates by 3-MeV Au 2þ irradiation. This indicates that irradiation using an industrially practical ion beam, which generally has kinetic energy less than 5 MeV, can provide a substantial increase in the in-field current performance of high-temperature superconductor films. Transmission electron microscopy results show that pointlike defects smaller than 6 nm in diameter were created in the films by the irradiation. V C 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4769836]One of the most significant hurdles in commercialization of electric-power devices using high-temperature superconductors (HTSC) is degraded critical-current-density (J c ) in magnetic fields. 1 In 2004, Macmanus-Driscoll et al. addressed this challenge by precipitating BaZrO 3 in YBa 2 Cu 3 O 7 (YBCO) films, 2 which work as artificial pinning centers (APCs) of vortices. 3 However, precise control of the secondary phase in shape 4 and alignment 5 has recently been recognized as vital to maximize J c and requires highly sophisticated synthesis techniques. Post-growth ion irradiation 6-12 is an easier route for such microstructure engineering, since it can control the properties of irradiation defects (size, shape, density, and alignment) by external parameters (ion mass, energy, fluence, and incident angle) without altering the growth conditions of a target material. 8,11 The following two reasons explain mainly why the irradiation approach to APC introduction has not received much attention during the recent development of second-generation HTSC wires, which consist of an epitaxial HTSC film on a metallic tape. The first reason is that previously observed J c improvements were substantial only in the bulk material but not in films, 1 which are a naturally pinning-center-rich form of the material. 13 The second is that measurable improvement in films was attained through the use of extremely high-energy ions (from hundreds MeV to GeV) generated by industrially impractical accelerators. 7,10-12 Indeed, previous ion-irradiation experiments for improving the current properties of HTSC heavily focused on the high-ion-energy range called electronic-stopping regime (>100 MeV), where incident ions lose their kinetic energy by the electronic excitation of target atoms. In that regime, continuous columnar defects can be fabricated along ion tracks 8,9,11 in perfect accordance with a long-accepted "consensus" that a cylindrical APC is most effective for increasing J c . 7,14 Conversely, despite its industrial affinity, ion irradiation in the nuclear-stopping regime (<5 MeV), where ions are decelerated by elastic collisions, has lacked an extensive investigation in the context of in-field-J c enhancement, 15-17 based on an assumption that expected point-like defects 9,11 are not as effective as continuous ones.In this letter, we propose reconsideration of these trends in the study...

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confidence: 97%

4-fold enhancement in the critical current density of YBa2Cu3O7 films by practical ion irradiation

Matsui

Ogiso

Yamasaki

et al. 2012

Applied Physics Letters

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“…Indeed, as shown in Ref. 17, introduction of structural defects may lead to a decrease in the critical current density j c at low magnetic fields and increase of j c at high fields.…”

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confidence: 97%

Spatially resolved studies of chemical composition, critical temperature, and critical current density of a YBa2Cu3O7−δ thin film

Gaevski

Bobyl

Shantsev

et al. 1998

Journal of Applied Physics

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Spatially-resolved studies of a YBa2Cu3O 7−δ thin film bridge using electron probe microanalysis (EPMA), low-temperature scanning electron microscopy (LTSEM), and magneto-optical flux visualization (MO) have been carried out. Variations in chemical composition along the bridge were measured by EPMA with 3 µm resolution. Using LTSEM the spatial distributions of the critical temperature, Tc, and of the local transition width, ∆Tc, were determined with 5 µm resolution. Distributions of magnetic flux over the bridge in an applied magnetic field have been measured at 15 and 50 K by magneto-optical technique. The critical current density jc as a function of coordinate along the bridge was extracted from the measured distributions by a new specially developed method. Significant correlations between jc, Tc, ∆Tc and cation composition have been revealed. It is shown that in low magnetic fields deviation from the stoichiometric composition leads to a decrease in both Tc and jc. The profile of jc follows the Tc-profile on large length scales and has an additional fine structure on short scales. The profile of jc along the bridge normalized to its value at any point is almost independent of temperature.

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“…Columnar pins, usually artificially produced by high energy ion irradiation or nano technique, can strongly affect the dynamic and thermodynamic properties of vortex matter [1,2]. Columnar pins can increase critical current, especially near matching field B φ where the number of vortices equals the number of pins [3][4][5][6][7][8]. Periodic columnar pin was found more effective in raising the critical current and raising the melting line to high temperature, especially at the matching field B φ , at its multiples B=nB φ , and at its fractions B= n 1 B φ [7,9,10].…”

Section: Introductionmentioning

confidence: 99%

Ground State and Transport Property in Superconductors with Artificial Pinning Arrays

Ren

Zhou

Zheng

et al. 2011

AMR

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The dynamics of a two-dimensional vortex system in superconductors with periodic artificial columnar pinning is studied. The ground state at field B = 3Bf can be either anisotropic or isotropic, dependent on pinning strength and size, here Bf is the matching field where the number of vortices equals that of pins. The transport curves are dependent on the ground vortex structures and anisotropic ground structure may result in anisotropic velocity-force curve. Results indicate that the ground structure can be detected from the transport property. We also discover that a jump in velocity-force curve accompanies a structure transition.

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Effects of 1-MeV proton irradiation in Hg-based cuprate thin films

Cited by 14 publications

References 34 publications

4-fold enhancement in the critical current density of YBa2Cu3O7 films by practical ion irradiation

4-fold enhancement in the critical current density of YBa2Cu3O7 films by practical ion irradiation

Spatially resolved studies of chemical composition, critical temperature, and critical current density of a YBa2Cu3O7−δ thin film

Ground State and Transport Property in Superconductors with Artificial Pinning Arrays

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