Role of flux pinning in high temperature superconductors. Observed pinning force density is compared with the predictions of the larkinovchinnikov theory and the coherent potential approximation theory. The book deals with the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, hightemperature and mgb2 superconductors. Similarly, in superconducting electronic devices and bulk superconductors used as permanent magnets, the prevention of flux motion through pinning is critical in.
Flux pinning is desirable in hightemperature ceramic superconductors to prevent flux creep, which can create a pseudo resistance and depress both critical current density and critical field. Flux pinning in superconductors springer series in solid. Flux pinning mechanisms in type ii superconductors. Pdf magnetooptical studies of flux pinning in high. Fluxpinning is desirable in hightemperature ceramic superconductors in order to prevent fluxcreep, which can create a pseudoresistance and depress jc and hc.
Magnetic relaxation, flux pinning and critical currents in. Kiuchi department of computer science and electronics, kyushu institute of technology, 6804 kawazu, iizuka 820, japan abstract the flux pinning properties in high temperature superconductors are strongly influenced by ther. Flux pinning in superconductors teruo matsushita springer. Flux pinning in superconductors teruo matsushita springer 201112 517 pages english pdf. This provides the stability of a levitating magnet. Note that flux pinning can only occur in typeii superconductors. Langhorn school of metallurgy and materials, university of birmingham screen printed thick film technology is recognised as an inexpensive and. Flux pinning by nano particles embedded in polycrystalline y. Flux pinning in superconducting nbti wires with nb. The statistical theory clarified that the nonzero pinning force. Second magnetization peak effect, vortex dynamics and flux. Flux pinning in superconductors springer series in solidstate sciences matsushita, teruo on.
Experimenting with a superconducting levitation train. Theories on the summation of randomly directed individual pinning forces to estimate the pinning force density are described based on the historical understanding of the pinning phenomena. Flux pinning by platinum and rhodium in high temperature superconductors platinum additions to ybco thick films improve critical current densities and superconducting properties by j. Scaling laws for flux pinning in hard superconductors. Us5226947a niobiumtitanium superconductors produced by. Flux pinning by platinum and rhodium in high temperature.
This demonstration with high temperature superconductors indicates that they are of. Addition of nanoparticle dispersions to enhance flux pinning. Flux pinning in superconductors wiley online library. The influence of the flux pinning on the vortex phase diagram in high tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of superconductor, specimen size and electric field strength. Flux pinning mechanisms in graphene doped mgb 2 superconductors k. Teruo matsushita flux pinning in superconductors 2006. Sanders a dissertation submitted to the graduate faculty in partial fulfillment of the. Pinning the motion of its magnetic field lines also means stopping the motion of the magnet. Introduction to superconductivity video about type 1 superconductors.
Addition of nanoparticle dispersions to enhance flux. Because of this, flux pinning turns out to be a highly complex phenomenon. The setup enables to test parameters like stability, speed, and safety, of the superconducting train for various gaps ranging between 1 mm to 15 mm between the. Thus, the threshold problem was actually resolved and it was shown that the pinning loss is of a hysteresis nature even for very weak pinning centers.
The main motivation for using type ii superconductors in these materials the. Flux pinning is the phenomenon where a superconductor is pinned in space above a magnet. Method and composition for improving flux pinning and critical current in. Fluxpinning is only possible when there are defects in the crystalline structure of the superconductor usually resulting from grain boundaries or impurities. Flux pinning is desirable in hightemperature ceramic superconductors to prevent flux creep, which can create a pseudoresistance and depress both critical current density and critical field. The flux pinning enhancement of type ii superconductors with defects have been studied in both copperoxide high and lowtemperature superconductor materials 3,4,14. Lichtenberger iowa state university follow this and additional works at. Processing, flux pinning and application of bisrcacuo. Meissner effect science from scratch short video from imperial college london about the meissner effect and levitating trains of the future. The nonsuperconducting inclusions act as pinning centers in the superconductor, increasing the critical current thereof. Langhorn school of metallurgy and materials, university of birmingham screen printed thick film technology is recognised as an inexpensive and effective means for the production of. The book covers the flux pinning mechanisms and properties and the electromagnetic.
Second magnetization peak effect, vortex dynamics and flux pinning in 112type superconductor ca 0. Flux pinning in superconductors springer series in solidstate sciences. Magnetooptical studies of flux pinning in hightemperature superconductors article pdf available in international journal of materials research formerly zeitschrift fuer metallkunde. Expressions for fluxpinning in type ii superconductors are derived from considerations of the nature of the interaction between individual fluxlines and pinningcentres, and of. Editorial full text access special issue on processing, flux pinning, and application of bisrcacuo hightemperature superconductors. High field flux pinning and the upper critical field of nbti superconductors.
The intergranular josephson vortex pinning is found to be. Us5430008a method and composition for improving flux. Fluxpinninginduced stress and magnetostriction in bulk. Flux pinning in superconductors 4 summation theories on pinning force density. The elementary interaction force fp can be accurately computed for such defects if their size is known from transmission electron microscopy. Extrinsic twodimensional flux pinning centers in mgb2. Magnetic flux motion and flux pinning in superconductors.
Method and composition for improving flux pinning and critical current in superconductors. Fietz and webb first demonstrated in dilute nb alloys that the peak in f p scales as h c 2 t 2. The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, hightc and mgb 2 superconductors. This demonstration with high temperature superconductors indicates that they are of typeii. Feb 18, 20 70046 superconductor meissner effect and flux pinning tute v0434h. Magnetic flux motion and flux pinning in superconductors by steven c. To understand the origin of the difference in behavior requires a microscopic description of the. Degradation of a hightemperature superconductors properties due to flux creep is a limiting factor in the use of these superconductors. Inhomogeneities always exist in real superconducting materials. Pdf we study magnetic flux interacting with arrays of pinning sites aps placed on vertices of hyperbolic tesselations ht. Teruo matsushita flux pinning in superconductors 2006 springer. Superconductors formed by powder metallurgy have a matrix of niobiumtitanium alloy with discrete pinning centers distributed therein which are formed of a compatible metal. Carbon can be considered as the most successful dopant for enhancing h c2, as it causes strong.
Pdf high field flux pinning and the upper critical field. Summation curves for flux pinning in superconductors. Pdf high field flux pinning and the upper critical field of. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial nb pins in nbti, etc. Pdf fundamental electromagnetic phenomena in superconductors. The artificial pinning centers in the nbti matrix are reduced in size by processing steps to sizes on the order of the coherence length, typically in the range of 1 to 10 nm. High field flux pinning and the upper critical field of nbti superconductors article pdf available in ieee transactions on applied superconductivity 72. Magnetic ilux motion and flux pinning in superconductors sanders, steven castle, ph. Degradation of a hightemperature superconductor s properties due to flux creep is a limiting factor in the use of these superconductors. Pdf magnetic flux pinning in superconductors with hyperbolic. Uniform graphene encapsulation of the boron powders was achieved by the hydrothermal method with highly dispersed graphene oxide as the precursor. Expressions for fluxpinning in type ii superconductors are derived from considerations of the nature of the interaction between individual fluxlines and pinningcentres, and of the geometry of the pinningcentres. The possibility of flux line dislocations flds and fld dipole participating in this plastic shear process may be important for weaker pinning materials where the pin spacing is large but for hard superconductors, where line pins are likely to be closely spaced, the chances of finding an fld source between pins is negligible.
Flux pinning on nanosized defects and critical current in htc. Expressions for flux pinning in type ii superconductors are derived from considerations of the nature of the interaction between individual flux lines and pinning centres, and of the geometry of the pinning centres. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction. Magnetic relaxation, flux pinning and critical currents in superconductors karl s. Aug 19, 2004 the flux pinning enhancement of type ii superconductors with defects have been studied in both copperoxide high and lowtemperature superconductor materials 3,4,14. Extrinsic twodimensional flux pinning centers, via grapheneencapsulated boron powder as precursors, have been introduced into mgb2 superconductors by means of in situ and diffusion sintering methods. Flux pinning is only possible when there are defects in the crystalline structure of the superconductor usually resulting from grain boundaries or impurities. However, because of its extreme importance for the technical applications of the cuprate superconductors, the subject of flux pinning has recently attracted a large amount of research and development.
Flux pinning in irradiated superconductors having either dislocation. These fac tors are directly related to the flux pinning of quantized magnetic flux lines in. When they move, the flux line lattice fll dissipates energy and the superconductor eventually goes normal. The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, hightc and mgb2 superconductors. The structural characterisation of all samples has been carried out by xraydiffraction xrd and transmission electron microscopy. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed. If the data for voids and dislocation loops are plotted as q. Aug 18, 2008 flux pinning in irradiated superconductors having either dislocation. R 0transition temperaturesb is a state variablemeissner effectenergy gap giaeverbcs model. Flux pinning is desirable in hightemperature ceramic superconductors in order to prevent flux creep, which can create a pseudoresistance and depress jc and hc. The magnetization curve is reversible for an ideal superconductor. Type i1 superconductors permit limited flux penetration in the form of flux quanta or fluxoids. Flux pinning in superconductors wimbush major reference. Data exist for a range of defects for which fp varies by over a factor of 104.
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