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Full-Text Articles in Physical Sciences and Mathematics
Dynamic Magneto-Optical Imaging Of Superconducting Thin Films, Frederick Wells, Alexey V. Pan, Stephen Wilson, Igor Golovchanskiy, Sergey Fedoseev, Anatoly B. Rosenfeld
Dynamic Magneto-Optical Imaging Of Superconducting Thin Films, Frederick Wells, Alexey V. Pan, Stephen Wilson, Igor Golovchanskiy, Sergey Fedoseev, Anatoly B. Rosenfeld
Australian Institute for Innovative Materials - Papers
We present a novel method for analysis of superconducting thin films using dynamic magneto-optical imaging, revealing hallmarks of flux penetration with temporal resolution around 1 ms (in the present work) or better. This method involves investigation of transient field and dynamic current distributions, which are calculated by an inversion procedure on the Biot-Savart Law, which we show to be valid under dynamic conditions. We compare and discuss the flux front penetration speed and evolution of current distribution in high quality YBa2Cu3O${}_{7-\delta }$ thin films with that of samples deliberately damaged in such a way as to reduce critical current density …
Evaluation Of Persistent-Mode Operation In A Superconducting Mgb2 Coil In Solid Nitrogen, Dipakkumar Patel, Md Shahriar Hossain, Khay Wai W. See, Wenbin Qiu, Hiroki Kobayashi, Zongqing Ma, Seong Jun Kim, Jonggi Hong, Jin Yong Park, Seyong Choi, Minoru Maeda, Mohammed Shahabuddin, Matthew A. Rindfleisch, Michael Tomsic, S X. Dou, Jung Ho Kim
Evaluation Of Persistent-Mode Operation In A Superconducting Mgb2 Coil In Solid Nitrogen, Dipakkumar Patel, Md Shahriar Hossain, Khay Wai W. See, Wenbin Qiu, Hiroki Kobayashi, Zongqing Ma, Seong Jun Kim, Jonggi Hong, Jin Yong Park, Seyong Choi, Minoru Maeda, Mohammed Shahabuddin, Matthew A. Rindfleisch, Michael Tomsic, S X. Dou, Jung Ho Kim
Australian Institute for Innovative Materials - Papers
We report the fabrication of a magnesium diboride (MgB2) coil and evaluate its persistent-mode operation in a system cooled by a cryocooler with solid nitrogen (SN2) as a cooling medium. The main purpose of SN2 was to increase enthalpy of the cold mass. For this work, an in situ processed carbon-doped MgB2 wire was used. The coil was wound on a stainless steel former in a single layer (22 turns), with an inner diameter of 109 mm and height of 20 mm without any insulation. The two ends of the coil were then joined to make a persistent-current switch to …
Metal Frame As Local Protection Of Superconducting Films From Thermomagnetic Avalanches, Pavlo Mikheenko, J I. Vestgarden, Supratim Chaudhuri, I J. Maasilta, Y Galperin, Tom H. Johansen
Metal Frame As Local Protection Of Superconducting Films From Thermomagnetic Avalanches, Pavlo Mikheenko, J I. Vestgarden, Supratim Chaudhuri, I J. Maasilta, Y Galperin, Tom H. Johansen
Australian Institute for Innovative Materials - Papers
Thermomagnetic avalanches in superconducting films propagating extremely fast while forming unpredictable patterns, represent a serious threat for the performance of devices based on such materials. It is shown here that a normal-metal frame surrounding a selected region inside the film area can provide efficient protection from the avalanches during their propagation stage. Protective behavior is confirmed by magneto-optical imaging experiments on NbN films equipped with Cu and Al frames, and also by performing numerical simulations. Experimentally, it is found that while conventional flux creep is not affected by the frames, the dendritic avalanches are partially or fully screened by them. …
Nanodroplets For Stretchable Superconducting Circuits, Long Ren, Jincheng Zhuang, Gilberto Casillas, Haifeng Feng, Yuqing Liu, Xun Xu, Yundan Liu, Jun Chen, Yi Du, Lei Jiang, Shi Xue Dou
Nanodroplets For Stretchable Superconducting Circuits, Long Ren, Jincheng Zhuang, Gilberto Casillas, Haifeng Feng, Yuqing Liu, Xun Xu, Yundan Liu, Jun Chen, Yi Du, Lei Jiang, Shi Xue Dou
Australian Institute for Innovative Materials - Papers
The prospective utilization of nanoscale superconductors as micro/nanocoils or circuits with superior current density and no electrical resistance loss in next-generation electronics or electromagnetic equipment represents a fascinating opportunity for new microsystem technologies. Here, a family of superconducting liquid metals (Ga-In-Sn alloys) and their nanodroplets toward printable and stretchable superconducting micro/nanoelectronics is developed. By tuning the composition of liquid metals the highest superconducting critical temperature (Tc) in this family can be modulated and achieved as high as 6.6 K. The liquid metal nanodroplets retain their bulk superconducting properties and can be easily dispersed in different solvents as inks. The printable …
Improved Superconducting Properties In The Mg11b2 Low Activation Superconductor Prepared By Low-Temperature Sintering, Fang Cheng, Yongchang Liu, Zongqing Ma, M Shahriar Al Hossain, Mehmet Somer
Improved Superconducting Properties In The Mg11b2 Low Activation Superconductor Prepared By Low-Temperature Sintering, Fang Cheng, Yongchang Liu, Zongqing Ma, M Shahriar Al Hossain, Mehmet Somer
Australian Institute for Innovative Materials - Papers
Mg11B2 has a great application prospect in the superconducting coils for fusion reactor as the "low activation superconductors". The un-doped Mg11B2 and Cu-doped Mg11B2 bulks using 11B as a boron precursor were fabricated by low-temperature sintering in present work. It was found that the prepared Mg11B2 low activation superconductors exhibit better Jc performance than all of other Mg11B2 samples reported in previous studies. As for Cu doped Mg11B2, minor Cu addition can obviously improve the Mg11B2 grain crystallization and reduce the amount of MgO impurity. Hence, improved grain connectivity and higher Jc at low fields is obtained in Cu doped …
Giant Enhancement In Critical Current Density, Up To A Hundredfold, In Superconducting Nafe0.97co0.03 As Single Crystals Under Hydrostatic Pressure, Babar Shabbir, Xiaolin Wang, Shaban Reza Ghorbani, A-Li Wang, S X. Dou, X.H Chen
Giant Enhancement In Critical Current Density, Up To A Hundredfold, In Superconducting Nafe0.97co0.03 As Single Crystals Under Hydrostatic Pressure, Babar Shabbir, Xiaolin Wang, Shaban Reza Ghorbani, A-Li Wang, S X. Dou, X.H Chen
Australian Institute for Innovative Materials - Papers
Tremendous efforts towards improvement in the critical current density "Jc" of iron based superconductors (FeSCs), especially at relatively low temperatures and magnetic fields, have been made so far through different methods, resulting in real progress. Jc at high temperatures in high fields still needs to be further improved, however, in order to meet the requirements of practical applications. Here, we demonstrate a simple approach to achieve this. Hydrostatic pressure can significantly enhance Jc in NaFe0.97Co0.03As single crystals by at least tenfold at low field and more than a hundredfold at high fields. …
Ray Optics Behavior Of Flux Avalanche Propagation In Superconducting Films, Pavlo Mikheenko, Tom H. Johansen, Supratim Chaudhuri, I J. Maasilta, Y Galperin
Ray Optics Behavior Of Flux Avalanche Propagation In Superconducting Films, Pavlo Mikheenko, Tom H. Johansen, Supratim Chaudhuri, I J. Maasilta, Y Galperin
Australian Institute for Innovative Materials - Papers
Experimental evidence of wave properties of dendritic flux avalanches in superconducting films is reported. Using magneto-optical imaging the propagation of dendrites across boundaries between a bare NbN film and areas coated by a Cu layer was visualized, and it was found that the propagation is refracted in full quantitative agreement with Snell's law. For the studied film of 170 nm thickness and a 0.9μm thick metal layer, the refractive index was close to n=1.4. The origin of the refraction is believed to be caused by the dendrites propagating as an electromagnetic shock wave, similar to damped modes …
Improving Fault Ride-Through Capability Of Dfig Based Wind Generators By Using Bridge-Type Superconducting Fault Current Limiter, Mehrdad Tarafdar Hagh, Kashem M. Muttaqi, Danny Sutanto, Md Shahriar Hossain, Ahmed M. Haidar
Improving Fault Ride-Through Capability Of Dfig Based Wind Generators By Using Bridge-Type Superconducting Fault Current Limiter, Mehrdad Tarafdar Hagh, Kashem M. Muttaqi, Danny Sutanto, Md Shahriar Hossain, Ahmed M. Haidar
Australian Institute for Innovative Materials - Papers
This paper proposes series connection of a diode bridge-type superconducting fault current limiter (SFCL) with rotor side converter (RSC) of a double fed induction generator (DFIG) based wind turbine. The proposed SFCL improves the fault ride through (FRT) capability of DFIG and prevents the RSC from damaging fault currents. Because of using superconductor DC coil, there is not any power loss during fault or normal operation of system. The proposed SFCL does not have any considerable affect in wind turbine's operation during normal condition. It is not necessary to use any measurement and control systems, too. The SFCL returns to …
Detection Of A Superconducting Phase In A Two-Atom Layer Of Hexagonal Ga Film Grown On Semiconducting Gan(0001), Hui-Min Zhang, Yi Sun, Wei Li, Jun-Ping Peng, Canli Song, Ying Xing, Qinghua Zhang, Jia-Qi Guan, Zhi Li, Yanfei Zhao, Shuaihua Ji, Lili Wang, Ke He, Xi Chen, Lin Gu, Langsheng Ling, Mingliang Tian, Lian Li, X. C Xie, Jianping Liu, Hui Yang, Qi-Kun Xue, Jian Wang, Xu-Cun Ma
Detection Of A Superconducting Phase In A Two-Atom Layer Of Hexagonal Ga Film Grown On Semiconducting Gan(0001), Hui-Min Zhang, Yi Sun, Wei Li, Jun-Ping Peng, Canli Song, Ying Xing, Qinghua Zhang, Jia-Qi Guan, Zhi Li, Yanfei Zhao, Shuaihua Ji, Lili Wang, Ke He, Xi Chen, Lin Gu, Langsheng Ling, Mingliang Tian, Lian Li, X. C Xie, Jianping Liu, Hui Yang, Qi-Kun Xue, Jian Wang, Xu-Cun Ma
Australian Institute for Innovative Materials - Papers
The recent observation of the superconducting state at atomic scale has motivated the pursuit of exotic condensed phases in two-dimensional (2D) systems. Here we report on a superconducting phase in twomonolayer crystalline Ga films epitaxially grown on wide-band-gap semiconductor GaN(0001). This phase exhibits a hexagonal structure and only 0.552 nm in thickness, nevertheless, brings about a superconducting transition temperature Tc as high as 5.4 K, confirmed by in situ scanning tunneling spectroscopy and ex situ electrical magnetotransport and magnetization measurements. The anisotropy of critical magnetic field and Berezinski-Kosterlitz-Thouless-like transition are observed, typical for the 2D superconductivity. Our results demonstrate a …
Mgb2 Superconducting Joints For Persistent Current Operation, Dipakkumar Patel, Md S. Hossain, Khay Wai W. See, Xun Xu, Shaon Barua, Zongqing Ma, Seyong Choi, Mike Tomsic, Jung Ho Kim
Mgb2 Superconducting Joints For Persistent Current Operation, Dipakkumar Patel, Md S. Hossain, Khay Wai W. See, Xun Xu, Shaon Barua, Zongqing Ma, Seyong Choi, Mike Tomsic, Jung Ho Kim
Australian Institute for Innovative Materials - Papers
High-performance superconducting joints are essential for realizing persistent-mode magnets. Herein, we propose a concept and fabrication of such superconducting joints, which yielded reliable performance in the operating temperature range of 4.2-25 K. MgB2-MgB2 joints in magnets are known to result in deterioration of localized electrical, thermal, and mechanical properties. To overcome these problems, the ends of the two wires are inserted into a pellet press, which is then filled with a mixture of unreacted magnesium and boron powders, followed by heat treatment. The critical current capacity and joint resistance were precisely evaluated by the standard four-probe method …
Ultra-High Performance, High-Temperature Superconducting Wires Via Cost-Effective, Scalable, Co-Evaporation Process, Ho-Sup Kim, Sang-Soo Oh, Hong-Soo Ha, Dojun Youm, Seung-Hyun Moon, Jung Ho Kim, S X. Dou, Yoon-Uk Heo, Sung-Hun Wee, Amit Goyal
Ultra-High Performance, High-Temperature Superconducting Wires Via Cost-Effective, Scalable, Co-Evaporation Process, Ho-Sup Kim, Sang-Soo Oh, Hong-Soo Ha, Dojun Youm, Seung-Hyun Moon, Jung Ho Kim, S X. Dou, Yoon-Uk Heo, Sung-Hun Wee, Amit Goyal
Australian Institute for Innovative Materials - Papers
Long-length, high-temperature superconducting (HTS) wires capable of carrying high critical current, Ic, are required for a wide range of applications. Here, we report extremely high performance HTS wires based on 5 μm thick SmBa2Cu3O7 − δ (SmBCO) single layer films on textured metallic templates. SmBCO layer wires over 20 meters long were deposited by a cost-effective, scalable co-evaporation process using a batch-type drum in a dual chamber. All deposition parameters influencing the composition, phase, and texture of the films were optimized via a unique combinatorial method that is broadly applicable for co-evaporation of other promising complex materials containing several cations. …
The Formation Of Nano-Layered Grains And Their Enhanced Superconducting Transition Temperature In Mg-Doped Fese0.9 Bulks, Feng Lan, Zongqing Ma, Yongchang Liu, Ning Chen, Qi Cai, Huijun Li, Shaon Barua, Dipakkumar Patel, Md Shahriar Hossain, Jung Ho Kim, S X. Dou
The Formation Of Nano-Layered Grains And Their Enhanced Superconducting Transition Temperature In Mg-Doped Fese0.9 Bulks, Feng Lan, Zongqing Ma, Yongchang Liu, Ning Chen, Qi Cai, Huijun Li, Shaon Barua, Dipakkumar Patel, Md Shahriar Hossain, Jung Ho Kim, S X. Dou
Australian Institute for Innovative Materials - Papers
To search a proper dopant to further improve superconductivity in 11 type Fe-based superconductors makes sense to both their superconductivity mechanism and possible technological applications. In present work, Mg doped FeSe polycrystalline bulks were obtained by a two-step solid-state reaction method. Even though there are many MgSe and iron impurities existing in the Mg heavy doped FeSe bulks, they exhibit obviously increased Tc compared to undoped FeSe sample. It was found that Mg addition has little effect on the crystal lattice parameters of superconducting beta-FeSe, whereas leads to the formation of nano-layered grain structure consisted of MgSe and beta-FeSe …
Imaging The Electron-Boson Coupling In Superconducting Fese Films Using A Scanning Tunneling Microscope, Canli Song, Yi-Lin Wang, Yeping Jiang, Zhi Li, Lili Wang, Ke He, Xi Chen, Jennifer E. Hoffman, Xu-Cun Ma, Qi-Kun Xue
Imaging The Electron-Boson Coupling In Superconducting Fese Films Using A Scanning Tunneling Microscope, Canli Song, Yi-Lin Wang, Yeping Jiang, Zhi Li, Lili Wang, Ke He, Xi Chen, Jennifer E. Hoffman, Xu-Cun Ma, Qi-Kun Xue
Australian Institute for Innovative Materials - Papers
Scanning tunneling spectroscopy has been used to reveal signatures of a bosonic mode in the local quasiparticle density of states of superconducting FeSe films. The mode appears below Tc as a "dip-hump" feature at energy Ω ∼ 4.7kBTc beyond the superconducting gap Δ. Spectra on strained regions of the FeSe films reveal simultaneous decreases in Δ and Ω. This contrasts with all previous reports on other high-Tc superconductors, where Δ locally anticorrelates with Ω. A local strong coupling model is found to reconcile the discrepancy well, and to provide a unified picture of the electron-boson coupling in unconventional superconductors.
Microstructural And Crystallographic Imperfections Of Mgb2 Superconducting Wire And Their Correlation With The Critical Current Density, Mohammed Shahabuddin, Nasser S. Alzayed, Sangjun Oh, Seyong Choi, Minoru Maeda, Satoshi Hata, Yusuke Shimada, Md Shahriar Al Hossain, Jung Ho Kim
Microstructural And Crystallographic Imperfections Of Mgb2 Superconducting Wire And Their Correlation With The Critical Current Density, Mohammed Shahabuddin, Nasser S. Alzayed, Sangjun Oh, Seyong Choi, Minoru Maeda, Satoshi Hata, Yusuke Shimada, Md Shahriar Al Hossain, Jung Ho Kim
Australian Institute for Innovative Materials - Papers
A comprehensive study of the effects of structural imperfections in MgB2 superconducting wire has been conducted. As the sintering temperature becomes lower, the structural imperfections of the MgB2 material are increased, as reflected by detailed X-ray refinement and the normal state resistivity. The crystalline imperfections, caused by lattice disorder, directly affect the impurity scattering between the π and σ bands of MgB2, resulting in a larger upper critical field. In addition, low sintering temperature keeps the grain size small, which leads to a strong enhancement of pinning, and thereby, enhanced critical current density. Owing to both the impurity scattering and …
Nanosecond Voltage Pulses From Dendritic Flux Avalanches In Superconducting Nbn Films, P Mikheenko, A J. Qviller, J I. Vestgarden, S Chaudhuri, I J. Maasilta, Y M. Galperin, Tom H. Johansen
Nanosecond Voltage Pulses From Dendritic Flux Avalanches In Superconducting Nbn Films, P Mikheenko, A J. Qviller, J I. Vestgarden, S Chaudhuri, I J. Maasilta, Y M. Galperin, Tom H. Johansen
Australian Institute for Innovative Materials - Papers
Combined voltage and magneto-optical study of magnetic flux flow in superconducting NbN films is reported. The nanosecond-scale voltage pulses appearing during thermomagnetic avalanches have been recorded in films partially coated by a metal layer. Simultaneous magneto-optical imaging and voltage measurements allowed the pulses to be associated with individual flux branches penetrating the superconductor below the metal coating. From detailed characteristics of pulse and flux branches, the electrical field in the superconductor is found to be in the range of 5-50 kV/m, while the propagation speed of the avalanche during its final stage is found to be close to 5 km/s.
Effect Of Sintering Temperature On The Superconducting Properties Of Graphene Doped Mgb2, K S B De Silva, X Xu, Sanjeev Gambhir, D C K Wong, W X Li, Q Y. Hu
Effect Of Sintering Temperature On The Superconducting Properties Of Graphene Doped Mgb2, K S B De Silva, X Xu, Sanjeev Gambhir, D C K Wong, W X Li, Q Y. Hu
Australian Institute for Innovative Materials - Papers
A comprehensive study on the effects of sintering temperature on graphene-doped MgB2 superconductor was conducted. Graphene has emerged as an effective dopant that is capable of improving the critical current density (J-{\rm c}) and flux pinning at a very low doping level, with only a slight reduction of the critical temperature (T-{\rm c}). MgB2 undoped and graphene-doped bulk samples were prepared by the in situ method and sintered within a temperature range from 650 to 950 {\circ}\hbox{C}. It is surprising to note that at the doping level of 1 at.% the sample sintered at 850 {\circ}\hbox{C} shows a J\rm c …
Enhanced Pinning In Superconducting Thin Films With Graded Pinning Landscapes, M Motta, F Colauto, W A. Ortiz, J Fritzsche, J Cuppens, W Gillijns, V V. Moshchalkov, T H. Johansen, A W Sanchez, A Silhanek
Enhanced Pinning In Superconducting Thin Films With Graded Pinning Landscapes, M Motta, F Colauto, W A. Ortiz, J Fritzsche, J Cuppens, W Gillijns, V V. Moshchalkov, T H. Johansen, A W Sanchez, A Silhanek
Australian Institute for Innovative Materials - Papers
A graded distribution of antidots in superconducting a-Mo 79Ge21 thin films has been investigated by magnetization and magneto-optical imaging measurements. The pinning landscape has maximum density at the sample border, decreasing linearly towards the center. Its overall performance is noticeably superior than that for a sample with uniformly distributed antidots: For high temperatures and low fields, the critical current is enhanced, whereas the region of thermomagnetic instabilities in the field-temperature diagram is significantly suppressed. These findings confirm the relevance of graded landscapes on the enhancement of pinning efficiency, as recently predicted by Misko and Nori [Phys. Rev. B 85, 184506 …
The Flux Pinning Mechanism, And Electrical And Magnetic Anisotropy In Fe1.04te0.6se0.4 Superconducting Single Crystal, Mahboobeh Shahbazi-Manshadi, Xiaolin Wang, S X. Dou, H Fang, C T. Lin
The Flux Pinning Mechanism, And Electrical And Magnetic Anisotropy In Fe1.04te0.6se0.4 Superconducting Single Crystal, Mahboobeh Shahbazi-Manshadi, Xiaolin Wang, S X. Dou, H Fang, C T. Lin
Australian Institute for Innovative Materials - Papers
The temperature and magnetic field dependences of the magnetization and critical current density of Fe1.04Te0.6Se0.4 single crystals have been investigated, and the flux pinning mechanism has been analysed. The normalized pinning force (fp Fp/F p,max) vs. h(H/Hirr) curves, are scaled using the Dew-Hughes theory, f(h) ≈ hp(1 - h)q with p 1.35 and q 3.06. The angular dependence of the resistivity under different magnetic fields shows a dip-like structure, below the superconducting transition temperature. The anisotropic value of 2 was obtained using Ginzburg-Landau theory.
Nonlocal Electrodynamics Of Normal And Superconducting Films, J I. Vestgarden, P Mikheenko, Y M. Galperin, T H Johansen
Nonlocal Electrodynamics Of Normal And Superconducting Films, J I. Vestgarden, P Mikheenko, Y M. Galperin, T H Johansen
Australian Institute for Innovative Materials - Papers
Electrically conducting films in a time-varying transverse applied magnetic field are considered. Their behavior is strongly influenced by the self-field of the induced currents, making the electrodynamics nonlocal, and consequently difficult to analyze both numerically and analytically. We present a formalism which allows many phenomena related to superconducting and Ohmic films to be modeled and analyzed. The formalism is based on the Maxwell equations and a material current-voltage characteristics, linear for normal metals and nonlinear for superconductors, plus a careful account of the boundary conditions. For Ohmic films, we consider the response to a delta function source-field turned on instantly. …
Thermo-Magnetic Stability Of Superconducting Films Controlled By Nano-Morphology, V V. Yurchenko, K Ilin, J M. Meckbach, M Siegel, A J. Qviller, Y M. Galperin, Tom H. Johansen
Thermo-Magnetic Stability Of Superconducting Films Controlled By Nano-Morphology, V V. Yurchenko, K Ilin, J M. Meckbach, M Siegel, A J. Qviller, Y M. Galperin, Tom H. Johansen
Australian Institute for Innovative Materials - Papers
Appearance of dendritic magnetic flux avalanches in superconducting films, which are associated with thermo-magnetic instability (TMI), very often indicates serious limitations for the ultimate performance of superconducting devices made of type-II superconducting thin films. We demonstrate that the stability can be controlled by a thorough adjustment of samples morphology at nano-scale, which affects internal material parameters. By this, the metal coating, commonly used as for stabilization, becomes redundant. Most importantly, we directly show by the mean of magneto-optical imaging that introduction of nano-scaled disorder dramatically changes the mode of magnetic flux propagation in the superconductors, from uniform motion of individual …
Limiting Thermomagnetic Avalanches In Superconducting Films By Stop-Holes, F Colauto, J I. Vestgarden, A M H De Andrade, A A M Oliveira, Wilson Aires Ortiz, Tom H. Johansen
Limiting Thermomagnetic Avalanches In Superconducting Films By Stop-Holes, F Colauto, J I. Vestgarden, A M H De Andrade, A A M Oliveira, Wilson Aires Ortiz, Tom H. Johansen
Australian Institute for Innovative Materials - Papers
It is demonstrated that circular holes in superconducting films of Nb can arrest the propagation of thermomagnetic avalanches. The effect was found over a range of temperatures where the material is susceptible to this instability. For other hole shapes, like square and triangular, the sharp corners provoke secondary avalanches, thus extending the breakdown. Making use of circular stop-holes can become a practical way to limit thermomagnetic breakdown in superconducting films.
Enhancing Superconducting Properties Of Mgb2 Pellets By Addition Of Amorphous Magnetic Ni-Co-B Nanoparticles, Mislav Mustapic, Josip Horvat, Md Shahriar Hossain, Zeljko Skoko, S X. Dou
Enhancing Superconducting Properties Of Mgb2 Pellets By Addition Of Amorphous Magnetic Ni-Co-B Nanoparticles, Mislav Mustapic, Josip Horvat, Md Shahriar Hossain, Zeljko Skoko, S X. Dou
Australian Institute for Innovative Materials - Papers
Amorphous magnetic Ni-Co-B nanoparticles with an average size of 5 nm were added to precursor powders of MgB2 superconductor. The preparation procedure for MgB2 pellets was optimized for obtaining the best critical current density (Jc) at elevated magnetic fields. Addition of Ni-Co-B decreases the Jc for heat treatment of precursor powders at 650 ° C. Heat treatments at 770 ° C and higher improve Jc at 20 and 5 K. This improvement occurs at both temperatures through the increase of the effective connectivity between MgB2 crystals. Vortex pinning was enhanced at 5 K, but not at 20 K. Ni-Co-B nanoparticles …
Structurally Homogeneous Mgb2 Superconducting Wires Through Economical Wet Mixing Process, Md Shahriar A. Hossain, Ashkan Motaman, Xun Xu, Khay Way See, Ozlem Cicek, Hasan Agil, Ercan Ertekin, Ali Gencer, Kookchae Cheong, Minoru Maeda, S X. Dou
Structurally Homogeneous Mgb2 Superconducting Wires Through Economical Wet Mixing Process, Md Shahriar A. Hossain, Ashkan Motaman, Xun Xu, Khay Way See, Ozlem Cicek, Hasan Agil, Ercan Ertekin, Ali Gencer, Kookchae Cheong, Minoru Maeda, S X. Dou
Australian Institute for Innovative Materials - Papers
We evaluate the effects of the mixing process between the starting materials on the structural and superconducting properties of carbon-doped MgB2 wires. The critical current density, n-value, amount of MgO, and critical temperature are obviously dependent on the mixing process, while the microstructure, i.e., grain size, is not sensitive. In our study, the wet-mixing process in toluene enables more homogenous mixing between the starting materials, resulting in superior J(c) and n-value.
Quasi-One-Dimensional Intermittent Flux Behavior In Superconducting Films, A J. Qviller, V V. Yurchenko, Y M. Galperin, J I. Vestgarden, P B. Mozhaeva, J B. Hansen, T H. Johansen
Quasi-One-Dimensional Intermittent Flux Behavior In Superconducting Films, A J. Qviller, V V. Yurchenko, Y M. Galperin, J I. Vestgarden, P B. Mozhaeva, J B. Hansen, T H. Johansen
Australian Institute for Innovative Materials - Papers
Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa2Cu3O7-δ deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film. As the applied field is gradually increased, magneto-optical imaging reveals that flux penetrates via numerous quasi-one-dimensional jumps. The distribution of flux avalanche sizes follows a power law, and data collapse is obtained by finite-size scaling, with the depth of the flux front used as crossover length. The intermittent behavior shows no threshold …
Flux Distribution In Fe-Based Superconducting Materials By Magneto-Optical Imaging, Zhi Wei Lin, Jian Guo Zhu, You Guang Guo, Xiaolin Wang, S X. Dou, Tom H. Johansen, Xun Shi, K Y. Choi
Flux Distribution In Fe-Based Superconducting Materials By Magneto-Optical Imaging, Zhi Wei Lin, Jian Guo Zhu, You Guang Guo, Xiaolin Wang, S X. Dou, Tom H. Johansen, Xun Shi, K Y. Choi
Australian Institute for Innovative Materials - Papers
"This paper presents the magnetic flux distributions in Fe-based superconducting materials including single crystal of Ba(Fe1.9Ni0.1)As2 and Ba(Fe1.8Co0.2)As2, as well as polycrystalline SmFeO0.75F0.2As by means of magneto-optical imaging (MOI) technique. The single crystals were grown out of FeAs flux while polycrystalline sample was grown by hot-press. A MOI film with in-plan magnetization was used to visualize flux distributions at the sample surface. A series of magneto-optical images was taken when the samples were zero-field cooled and field cooled. The flux behavior, including penetration into and …
Magnetic And Superconducting Properties Of Spin-Fluctuation-Limited Superconducting Nanoscale Vnx, R Zeng, J Liu, G Du, W. X. Li, J Wang, J Horvat, S X. Dou
Magnetic And Superconducting Properties Of Spin-Fluctuation-Limited Superconducting Nanoscale Vnx, R Zeng, J Liu, G Du, W. X. Li, J Wang, J Horvat, S X. Dou
Australian Institute for Innovative Materials - Papers
"VNx nanoparticles and nanowires have been prepared by nitrifying V2O5 nanoparticles (NP) and nanowires (NW). The V2O5 NP and NW were synthesized by a facile hydrothermal method. Magnetic susceptibility (chi) and magnetization measurements showed long range superconducting ordering (LRSO) at the temperature of 5.8 K for NW, but there was no observation of LRSO (at least down to 2 K) for the NP sample, which is a much lower temperature than for the corresponding bulk, while both NP and NW showed the absence of long range magnetic ordering, at least down to 2 K. However, the chi data showed that …
Mechanism For Flux Guidance By Micrometric Antidot Arrays In Superconducting Films, J I. Vestgarden, V V. Yurchenko, R Wordenweber, T H. Johansen
Mechanism For Flux Guidance By Micrometric Antidot Arrays In Superconducting Films, J I. Vestgarden, V V. Yurchenko, R Wordenweber, T H. Johansen
Australian Institute for Innovative Materials - Papers
"A study of magnetic flux penetration in a superconducting film patterned with arrays of micron-sized antidots (microholes) is reported. Magneto-optical imaging (MOI) of a YBa(2)Cu(3)O(x) film shaped as a long strip with perpendicular antidot arrays revealed both strong guidance of flux and, at the same time, large perturbations of the overall flux penetration and flow of current. These results are compared with a numerical flux creep simulation of a thin superconductor with the same antidot pattern. To perform calculations on such a complex geometry, an efficient numerical scheme for handling the boundary conditions of the antidots and the nonlocal electrodynamics …
Very Strong Intrinsic Flux Pinning And Vortex Avalanches In (Ba, K)Fe2as2 Superconducting Single Crystals, Xiaolin Wang, Shaban R. Ghorbani, Sung-Ik Lee, S X. Dou, C T Lin, T H. Johansen, K.H Muller, Zhenxiang Cheng, Germanas Peleckis, M Shabazi, A.J Qviller, V Yurchenko, G.L Sun, D.L Sun
Very Strong Intrinsic Flux Pinning And Vortex Avalanches In (Ba, K)Fe2as2 Superconducting Single Crystals, Xiaolin Wang, Shaban R. Ghorbani, Sung-Ik Lee, S X. Dou, C T Lin, T H. Johansen, K.H Muller, Zhenxiang Cheng, Germanas Peleckis, M Shabazi, A.J Qviller, V Yurchenko, G.L Sun, D.L Sun
Australian Institute for Innovative Materials - Papers
We report that the (Ba,K)Fe2As2 crystal with Tc=32 K shows a pinning potential, U0, as high as 104 K, with U0 showing very little field dependence. The (Ba,K)Fe2As2 single crystals become isotropic at low temperatures and high magnetic fields, resulting in a very rigid vortex lattice, even in fields very close to Hc2. The isotropic rigid vortices observed in the two-dimensional (2D) (Ba,K)Fe2As2 distinguish this compound from 2D high-Tc cuprate superconductors with 2D vortices. The vortex avalanches were also observed at low …
Superconducting Properties Of Carbonaceous Chemical Doped Mgb2, Wenxian Li, S X. Dou
Superconducting Properties Of Carbonaceous Chemical Doped Mgb2, Wenxian Li, S X. Dou
Australian Institute for Innovative Materials - Papers
The discovery of superconductivity in magnesium diboride (MgB2: 39 K, in January 2001) (Nagamatsu et al., 2001) has generated enormous interest and excitement in the superconductivity community and the world in general, but especially among researchers into superconductivity in non-oxide and boron related compounds.
Fabrication And Superconducting Properties Of Highly Dense Mgb2 Bulk Using A Two-Step Sintering Method, Minoru Maeda, Yue Zhao, Yoshifumi Watanabe, Hiroaki Matsuoka, Y Kubota
Fabrication And Superconducting Properties Of Highly Dense Mgb2 Bulk Using A Two-Step Sintering Method, Minoru Maeda, Yue Zhao, Yoshifumi Watanabe, Hiroaki Matsuoka, Y Kubota
Australian Institute for Innovative Materials - Papers
We investigated on microstructure and superconducting properties of high-density MgB2superconductors synthesized by a heat-treatment method combining a short period of sintering at 1100°C with a following annealing at a low temperature. The two-step sintering method was found to achieve a coexistence of a high density and broadened XRD full width at half maximum (FWHM) of MgB2 peak in the samples. The onset of diamagnetism at 5 T was approximately 2 K higher than those of the samples heat-treated by single-step sintering at high or low temperatures. Different second-step annealing temperatures were examined in this work. …