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Spontaneous macroscopic magnetization at the superconducting transition temperature of YBa2Cu3O7-δ

Nature volume 404, pages 853–855 (2000)Cite this article

Abstract

A noteworthy feature of the high-temperature superconductors is the unconventional symmetry of the superconducting order parameter. Several experiments1,2,3 have established that the order parameter has a four-fold d x 2 - y 2 symmetry under rotation of the lattice (the order parameter of conventional superconductors is, in contrast, isotropic). An intriguing and much debated possibility is that, in certain cases, an additional imaginary component might be present, having an isotropic s-wave4,5,6 or dxy symmetry7,8,9,10. A consequence of a complex order parameter of the form d x 2 - y 2 + idxy is that it would break both reflection (parity, P) symmetry and time-reversal (T) symmetry, a clear signature of which would be the spontaneous appearance of a macroscopic magnetization at the superconducting transition temperature. Broken T symmetry has been reported5,11, but searches for the effects of combined P and T symmetry breaking have so far yielded null results12,13,14,15. Here we report the observation of a weak (∼10-5 gauss) magnetic field that appears spontaneously at the superconducting transition temperature of epitaxial thin films of YBa2Cu3O7-δ. The magnetic signal originates near the edges of the samples. One interpretation for this observation is that the order parameter carries an intrinsic angular momentum, related to the breaking of P and T symmetries, but other possibilities cannot yet be excluded.

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Figure 1: Schematic illustration of the experimental geometry and of the sample patterns.
Figure 2: Spontaneous magnetic field generated by a thin YBCO film plotted against temperature.
Figure 3: Total signal generated by a YBCO film cooled in an external magnetic field.
Figure 4: Magnitude of the spontaneous field jump plotted against film thickness.

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References

  1. Wollman,D. A, Van Harlingen,D. J., Giapintzakis, J. & Ginsberg,D. M. Evidence for d x 2 -y 2 pairing from magnetic field modulation of YBCo-Pb Josephson junctions. Phys. Rev. Lett. 74, 797–800 ( 1995).

    Article  ADS  CAS  Google Scholar 

  2. Tsuei,C. C. et al. Pairing symmetry in single layer Tl2Ba2CuO 6+δ. Science 271, 329– 332 (1996).

    Article  ADS  CAS  Google Scholar 

  3. Shen,Z. X. et al. Anomalously large gap anisotropy in the a-b plane of Bi 2Sr2CaCuO8. Phys. Rev. Lett. 70, 1553–1556 (1993).

    Article  ADS  CAS  Google Scholar 

  4. Sigrist,M. Time reversal symmetry breaking states in high temperature superconductors. Prog. Theor. Phys. (Jpn) 99, 899– 929 (1998).

    Article  ADS  CAS  Google Scholar 

  5. Covington,M., Aprili,M., Paraoanu,E. & Greene,L. H. Observation of surface induced broken time reversal symmetry in Yba2Cu3O 7-δ tunnel junctions. Phys. Rev. Lett. 79, 277–281 (1997).

    Article  ADS  CAS  Google Scholar 

  6. Fogelstrom,M., Rainer,D. & Sauls,J. A. Tunneling into current carrying states of high T c superconductors. Phys. Rev. Lett. 79, 281–284 (1997).

    Article  ADS  CAS  Google Scholar 

  7. Halperin,B. I., March-Russell,J. & Wilczek, F. Consequences of time reversal symmetry violation in models of high Tc superconductors. Phys. Rev. B 40, 8726–8744 ( 1989).

    Article  ADS  CAS  Google Scholar 

  8. Laughlin,R. B. Magnetic induction of d x 2 - y 2 + id xy order in high Tc superconductors. Phys. Rev. Lett. 80, 5188 –5191 (1998).

    Article  ADS  CAS  Google Scholar 

  9. Salkola,M. I & Schrieffer,J. R. Unusual states of inhomogeneous d x 2 - y 2 + id xy superconductors. Phys. Rev. B 58, R5952–R5255 (1998).

    Article  ADS  CAS  Google Scholar 

  10. Krishana,K, Ong,N. P., Li,Q., Gu,G. D. & Koshizuka, N. Plateaus observed in the field profile of thermal conductivity in the superconductor Bi2Sr2CaCu2O8 . Science 277, 83– 85 (1997).

    Article  CAS  Google Scholar 

  11. Krupke,R. & Deutscher,G. Anisotropic magnetic field dependence of zero bias anomaly of in-plane oriented (100) Yba2Cu3O 7-δ/In tunnel junctions. Phys. Rev. Lett. 83, 4634–4637 (1999).

  12. Kiefl,R. F. et al. Search for anomalous internal fields in high Tc superconductors as evidence for broken time reversal symmetry. Phys. Rev. Lett. 64, 2082–2085 (1990).

    Article  ADS  CAS  Google Scholar 

  13. Spielman,S. et al. Measurement of the spontaneous Kerr effect in Bi2Sr 2CaCuO8. Phys. Rev. Lett. 68, 3472–3475 (1992).

    Article  ADS  CAS  Google Scholar 

  14. Mathai,A., Gim,Y., Black,R. C., Amar,A. & Wellstood,F. C. Experimental proof of time reversal invariant order parameter with a π shift in YBa2Cu3O7-δ . Phys. Rev. Lett 74, 4523– 4526 (1995).

    Article  ADS  CAS  Google Scholar 

  15. Kirtley,J. R., Tsuei,C. C. & Moler,K. A. Temperature dependence of the half-integer magnetic flux quantum. Science 285, 1373– 1375 (1999).

    Article  CAS  Google Scholar 

  16. Pearl,J. Current distribution in superconducting films carrying quantized fluxoids. Appl. Phys. Lett. 5, 65– 66 (1964).

    Article  ADS  Google Scholar 

  17. Kirtley,J. R. et al. Distribution of magnetic flux in high Tc grain-boundary junctions enclosing hexagonal and triangular areas. Phys. Rev. B 51, 12057–12060 ( 1995).

    Article  ADS  CAS  Google Scholar 

  18. Sigrist,M. & Rice,T. M. Paramagnetic effect in high T c superconductors-a hint for d-wave superconductivity. J. Phys. Soc. Jpn 61, 4283–4286 (1992).

    Article  ADS  CAS  Google Scholar 

  19. Kawamura,H. & Li,M. S. Equilibrium phase with broken time reversal symmetry in ceramic high Tc superconductors. Phys. Rev. Lett. 78, 1556–1559 (1997).

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

We thank E. Zeldov for discussions. This work was supported by the Israel Science Foundation, The Heinrich Hertz Minerva Center for HTSC, and by the VPR Technion Fund for Promotion of Research.

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  1. Physics Department, Technion–Israel Institute of Technology, Haifa, 32000, Israel

    R. Carmi, E. Polturak, G. Koren & A. Auerbach

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  1. R. Carmi
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Correspondence to E. Polturak.

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Carmi, R., Polturak, E., Koren, G. et al. Spontaneous macroscopic magnetization at the superconducting transition temperature of YBa2Cu3O7-δ. Nature 404, 853–855 (2000). https://doi.org/10.1038/35009062

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