The addition of Pb in the superconductors of BiSrCaCuO system is very helpful for growth of the high-Tc phase (Tc 110K). We prepared a series of samples with nominal composition of Bi2-xPbxSr2Ca2Cu3Oy (0.1&lex&...The addition of Pb in the superconductors of BiSrCaCuO system is very helpful for growth of the high-Tc phase (Tc 110K). We prepared a series of samples with nominal composition of Bi2-xPbxSr2Ca2Cu3Oy (0.1&lex&le2). The zero resistance transition temperature Tc of 106K and the critical transport current density Jc of 1 × 103A/cm2 at 77K have been obtained for the samples of Bi2-xPbxSr2Ca2Cu3Oy (x=0.2 and 0.3). The X-ray diffraction analysis and measurement of AC magnetic susceptibility confirmed that the material is comprised of single high-Tc phase. We also report the magnetic properties of this material as well as the results of TEM observation.展开更多
Since the discovery of superconductivity of the BiSrCuO system at 20K, the work of synthesizing high Tc superconductors without rare-earths by adding some elements other than rare-earths in the BiSrCuO system has made...Since the discovery of superconductivity of the BiSrCuO system at 20K, the work of synthesizing high Tc superconductors without rare-earths by adding some elements other than rare-earths in the BiSrCuO system has made a lot of progress. Recently, N. Fukushima et al. have synthesized Bi4Sr4RE2Cu4O16+δ (RE = Nd, Eu or Y) by substituting RE for Ca in the Bi4Sr4Ca2Cu4O16+δ superconductor and revealed that it has a crystal structure identical with this superconductor, but it is an insulator. In this paper, the authors report the superconductivity and structure of the BiSrCaEuCuO compound synthesized by adding 5 at% of rare-earth Eu in the BiSrCaCuO system.展开更多
We report experimental investigation of the resistivity and Nernst effect in two-dimensional(2D)NbSe2 crystals.A strongly enhanced Nernst effect,100 times larger than that in bulk NbSe2,caused by moving vortices is ob...We report experimental investigation of the resistivity and Nernst effect in two-dimensional(2D)NbSe2 crystals.A strongly enhanced Nernst effect,100 times larger than that in bulk NbSe2,caused by moving vortices is observed in thin film.It is found that in the low temperature,high magnetic field regime,pinning effects show little dependence on the thickness and resistivity of the superconductor films.Strong Nernst signals persist above the superconducting transition,suggesting that the Nernst effect is a sensitive probe to superconducting fluctuations.A magnetic field induced superconductor-insulator transition(SIT)is evident,which is surprising in that such a SIT usually takes place in disordered dirty superconductors,while our samples are highly crystalline and close to the clean limit.Hence,our results expand the scope of SIT into 2D crystal clean superconductors.展开更多
We theoretically investigate the possibility of achieving a superconducting state in transition-metal dichalcogenide bilayers through intercalation, a process previously and widely used to achieve metal- lization and ...We theoretically investigate the possibility of achieving a superconducting state in transition-metal dichalcogenide bilayers through intercalation, a process previously and widely used to achieve metal- lization and superconducting states in novel superconductors. For the Ca-intercalated bilayers MoSs and WS2, we find that the superconducting state is characterized by an electron-phonon coupling constant larger than 1.0 and a superconducting critical temperature of 13.3 and 9.3 K, respectively. These results are superior to other predicted or experimentally observed two-dimensional conventional ＇superconductors and suggest that the investigated materials may be good candidates for nanoscale su- perconductors. More interestingly, we proved that the obtained thermodynamic properties go beyond the predictions of the mean-field Bardeen-Cooper-Schrieffer approximation and that the calculations conducted within the framework of the strong-coupling Eliashberg theory should be treated as those that yield quantitative results.展开更多
基金This work was supported by The National Center for Research and Development on Superconductivity.
文摘The addition of Pb in the superconductors of BiSrCaCuO system is very helpful for growth of the high-Tc phase (Tc 110K). We prepared a series of samples with nominal composition of Bi2-xPbxSr2Ca2Cu3Oy (0.1&lex&le2). The zero resistance transition temperature Tc of 106K and the critical transport current density Jc of 1 × 103A/cm2 at 77K have been obtained for the samples of Bi2-xPbxSr2Ca2Cu3Oy (x=0.2 and 0.3). The X-ray diffraction analysis and measurement of AC magnetic susceptibility confirmed that the material is comprised of single high-Tc phase. We also report the magnetic properties of this material as well as the results of TEM observation.
文摘Since the discovery of superconductivity of the BiSrCuO system at 20K, the work of synthesizing high Tc superconductors without rare-earths by adding some elements other than rare-earths in the BiSrCuO system has made a lot of progress. Recently, N. Fukushima et al. have synthesized Bi4Sr4RE2Cu4O16+δ (RE = Nd, Eu or Y) by substituting RE for Ca in the Bi4Sr4Ca2Cu4O16+δ superconductor and revealed that it has a crystal structure identical with this superconductor, but it is an insulator. In this paper, the authors report the superconductivity and structure of the BiSrCaEuCuO compound synthesized by adding 5 at% of rare-earth Eu in the BiSrCaCuO system.
基金the National Key Basic Research Program of China(Grant No.2016YFA0300600)the National Natural Science Foundation of China(Grant Nos.11574005 and 11774009).
文摘We report experimental investigation of the resistivity and Nernst effect in two-dimensional(2D)NbSe2 crystals.A strongly enhanced Nernst effect,100 times larger than that in bulk NbSe2,caused by moving vortices is observed in thin film.It is found that in the low temperature,high magnetic field regime,pinning effects show little dependence on the thickness and resistivity of the superconductor films.Strong Nernst signals persist above the superconducting transition,suggesting that the Nernst effect is a sensitive probe to superconducting fluctuations.A magnetic field induced superconductor-insulator transition(SIT)is evident,which is surprising in that such a SIT usually takes place in disordered dirty superconductors,while our samples are highly crystalline and close to the clean limit.Hence,our results expand the scope of SIT into 2D crystal clean superconductors.
文摘We theoretically investigate the possibility of achieving a superconducting state in transition-metal dichalcogenide bilayers through intercalation, a process previously and widely used to achieve metal- lization and superconducting states in novel superconductors. For the Ca-intercalated bilayers MoSs and WS2, we find that the superconducting state is characterized by an electron-phonon coupling constant larger than 1.0 and a superconducting critical temperature of 13.3 and 9.3 K, respectively. These results are superior to other predicted or experimentally observed two-dimensional conventional ＇superconductors and suggest that the investigated materials may be good candidates for nanoscale su- perconductors. More interestingly, we proved that the obtained thermodynamic properties go beyond the predictions of the mean-field Bardeen-Cooper-Schrieffer approximation and that the calculations conducted within the framework of the strong-coupling Eliashberg theory should be treated as those that yield quantitative results.
