Dependence of Irreversibility Field of Bi-2223 Silver-Sheathed Tape Wire on Different Electric Field Criteria Mitsuhiro Fukuda, Takeshi Kodama, Kazuo Shiraishi, Shoichi Nishimura, Edmund * *Soji Otabe, Masaru Kiuchi, Takanobu Kiss, Teruo Matsushita, Kikuo Itoh Abstract_ Dependence of the irreversibilitymfield(Bi)eonasurements. The number* * of filaments (f) was 59 and the electric field criterion (Ec) was measuredtforhaeBi-2223averaged width (w) * *and thickness (d) of the filaments silver-sheathed tape wire using various measuring methods. It was found that Biincreased monotonically withwtheeelec-re 320 ~m and 11 ~m, * *respectively. Tc measured from tric field criterion. A good agreement was obtainedDforCBisusceptibility was 11* *0 K. In all the measurements the between experiments and the theoretical analysismusingathegnetic field was appl* *ied parallel to the c-axis. flux creep-flow model. This implies that the resistive(prop-1)In the AC suscept* *ibility measurement the AC mag- erty of superconducting wires can be well described by the mechanism of flux creep and flow. netic field was applied parallel to* * the c-axis at various tem- Keywords_Irreversibility field, electric fieldpcriterion,efluxratures. The fre* *quency and the amplitude of AC mag- creep-flow model. netic field were 35.0 Hz and 0.1 mT* *, respectively. The irre- versibility temperature (Ti) was de* *termined by the temper- I.Introduction ature at which an imaginary AC susc* *eptibility appeared. Biwas determined from the magnetic * *field dependence of T is empirically known that the determinationTofithe. Iirreversibility field (Bi) is strongly influenced(by2both)In the current-volta* *ge characteristics measurement the electric field criterion (Ec) for the determinationuofstheing a four probe * *method, Jc was determined with the critical current density (Jc) and the criterioneoflJc(eJc).ctric field criterio* *n Ec = 10-4 V/m, and Jc = 1:0 x Hence, it is needed to describe Bias a function1of0Ecand7A=m2was used for the d* *etermination of Bi. Jc. In this study, we observed Biin a Bi-2223(silver-3)In the DC magnetizatio* *n measurement a SQUID mag- sheathed tape wire by various measuring methods:netometer was used. Jcwas deter* *mined by o imaginary AC susceptibility o current-voltage characteristic using a four probeJ = ___6_m____; method c w2df(3l - w) o DC magnetization hysteresis o current-voltage characteristic estimated fromwthehre-ere, m was the hystere* *sis7of magnetic2moment. For laxation of magnetization the determination of Bi, Jc= 1:0 x* * 10 A=m was used. The irreversibility field was also compared with(the4vor-)In the magnetic rela* *xation measurement, the electric tex glass-liquid transition field (Bg) obtainedffromitheeld(E) and the current * *density(J) were respectively esti- scaling of E-J curves. The experimental resultmwasacom-ted by pared with the theoretical analysis using the flux creep-flow 12m model. J = __________w2df(3l* *;- w) II.Experimental The measured specimen was a Bi-2223 silver-sheathed E = -___~0___. dm_: tape wire prepared by the powder-in-tube method. The 2df(l + w) dt sizes of specimen were 3:7 mm wide and 270 ~mthick. The tape was cut in a length of l = 4:2 mm for theTmagnetichen, Jc was determined a* *t E = 10-10V/m. Jc = 1:0 x 107 A=m2was used for the dete* *rmination of Bi. M. Fukuda is with Kyushu Institute of Technology,T680-4,hKawazu,e scaling of E* *-J curves was examined for the results Iizuka 820-8502, Japan (Telephone: +81-948-29-7683,oe-mail:btained in the meas* *urements (2) and (4) and the vortex fukuda@aquarius10.cse.kyutech.ac.jp) K. Shiraishi is with Kyushu University, 6-8-1,gHakozaki,lHigashi-ass-liquid tr* *ansition field (Bg) was determined. ku, Fukuoka 812-8581, Japan S. Nishimura is with Kyushu University, Fukuoka, JapanIII.Results and Discussi* *on E. S. Otabe is with Kyushu Institute of Technology, Iizuka Japan M. Kiuchi is with Kyushu University, Fukuoka,FJapanig. 1 shows Bidetermined wi* *th various measurements T. Kiss is with Kyushu University, Fukuoka,iJapann which different electric fi* *eld criteria are used and Bg T. Matsushita is with Kyushu Institute of Technology,eIizukasJapantimated from* * two current-voltage characteristics in the K. Itoh is with National Research InstitutelforoMetals,w3-13,and high electric* * field regions. Sakura, Tsukuba 305-0003, Japan Fig. 1.Irreversibility field of Bi-2223 silver-sheathedFig.D2.ependence of irr* *eversibility field on electric tape wire determined with different electricffieldield criteria at T = * *70 K. criteria and transition field. Fig. 2. shows Ec dependence of Biat T = 70 K under the condition of Jc= 1:0x107A=m2 . Bidepends largely on the electric field criterion for the definition of Jc. In the figure Bgis also shown for comparison. It is found that Bg also takes on a high value when the range of electric field is high. This is consistent with the previous measurement on a Y-123 thin film [1] and incompatible with the prediction of the vortex glass-liquid transition theory. The E-J characteristics can be calculated theoretically with the aid of the flux creep-flow model [2]. From the results Bican be estimated with the same Ec and Jc as in experiment. The temperature dependence of Biis compared between the experiment and the theory in Fig. 3. It is seen that the flux creep-flow model can describe Biin a wide range of the electric field. In the AC susceptibility measurement, the conditionsFofig.T3.he theoretical an* *alysed B (solid lines) com- the determination of Biare about Ec = 3:5 x 10-6 V/mpared with the experimental* * resultsi(symbols). and Jc = 1:0 x 105 A=m2. Hence, the value of Biis strongly influenced by the choice of these conditions. If we express the relationship between E and J as(E2/)Jn,The vortex glass-liquid t* *ransition field depends also we have n = 2.82 in the vicinity of the irreversibilityofield.n the range of el* *ectric field. This is incompatible with the Hence, a similar relationship Ec / Jncholds,pandrifethediction of the vortex g* *lass-liquid transition theory. same condition of Jc = 1:0 x 107 A=m2 is chosen, the corresponding value of Ec is Ec = 10-2 V/m. Thus, if References Bicould be obtained in the same conditions as[in1other]T. Nakamura, T. Kiss, Y.* * Hanayama, T. Matsushita, K. Funaki, measurements, Bifrom the AC susceptibility measurementM.sTakeouandpF.eIrie,r"Tr* *ansportcpropertiesoinnY1Ba2Cu3O7-ffiducting thin films over wide range of ele* *c@ would be located as shown by the solid triangleSinuFig.p2.ercond. X (1998) 581. Therefore, all the measurements seem to be described[well2]M. Kiuchi, K. Noguch* *i, T. Matsushita, T. Kato, T. Hirata and by the flux creep-flow model. K.BSato,i"Scaling-of2current-volt* *age2curves2in3superconductingsilver-sheathed tape wires", Physica C 278 (1997* *)@ IV.Summary The electric field criterion dependence of the irreversibil- ity field was measured for a Bi-2223 silver-sheathed tape wire and the following results were obtained: (1)Bidepends largely on the electric field criterion and this behavior can be well described by the flux creep-flow model in a wide range of the electric field.