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Cuprate superconductor

The unit cell of high-temperature cuprate superconductor BSCCO-2212

Cuprate superconductors are high temperature superconductors made of cuprates. They are layered materials, consisting of superconducting CuO2 layers separated by spacer layers.

History

Interest in cuprates sharply increased in 1986 with the discovery of high-temperature superconductivity in the Non-stoichiometric cuprate lanthanum barium copper oxide . The Tc for this material was 35 K, well above the previous record of 23K.[1] Thousands of publications examine the superconductivity in cuprates between 1986 and 2001,[2] and Bednorz and Müller were awarded the Nobel Prize in Physics only a year after their discovery.[3]

From 1986 to 2008, many cuprate superconductors were identified, the most famous being yttrium barium copper oxide (YBa2Cu3O7, "YBCO" or "1-2-3"). Another example is bismuth strontium calcium copper oxide (BSCCO or Bi2Sr2CanCun+1O2n+6-d) with Tc = 95–107 K depending on the n value. Thallium barium calcium copper oxide (TBCCO, TlmBa2Can−1CunO2n+m+2+δ) was the next class of high-Tc cuprate superconductors with Tc = 127 K observed in Tl2Ba2Ca2Cu3O10 (TBCCO-2223) in 1988.[4] The highest confirmed, ambient-pressure, Tc is 135 K, achieved in 1993 with the layered cuprate HgBa2Ca2Cu3O8+x.[5][6] Few months later, another team measured superconductivity above 150K in the same compound under applied pressure (153 K at 150 kbar).[7]

Structure

Cuprate superconductors usually feature copper oxides in both the oxidation state 3+ as well as 2+. For example, YBa2Cu3O7 is described as Y3+(Ba2+)2(Cu3+)(Cu2+)2(O2−)7. All superconducting cuprates are layered materials having a complex structure described as a superlattice of superconducting CuO2 layers separated by spacer layers where the misfit strain between different layers and dopants in the spacers induce a complex heterogeneity that in the superstripes scenario is intrinsic for high temperature superconductivity.

Applications

BSCCO superconductors already have large-scale applications. For example, tens of kilometers of BSCCO-2223 superconductive tape are being used (at 77 K) in the current leads of the Large Hadron Collider,[8] (but the main field coils are using low temperature superconductors).

References

  1. ^ J.G. Bednorz; K.A. Mueller (1986). "Possible high TC superconductivity in the Ba-La-Cu-O system". Z. Phys. B. 64 (2): 189–193. Bibcode:1986ZPhyB..64..189B. doi:10.1007/BF01303701.
  2. ^ Mark Buchanan (2001). "Mind the pseudogap". Nature. 409 (6816): 8–11. doi:10.1038/35051238. PMID 11343081.
  3. ^ Nobel prize autobiography
  4. ^ Sheng, Z. Z.; Hermann A. M. (1988). "Bulk superconductivity at 120 K in the Tl–Ca/Ba–Cu–O system". Nature. 332 (6160): 138–139. Bibcode:1988Natur.332..138S. doi:10.1038/332138a0.
  5. ^ Schilling, A.; Cantoni, M.; Guo, J. D.; Ott, H. R. (1993). "Superconductivity above 130 K in the Hg–Ba–Ca–Cu–O system". Nature. 363 (6424): 56–58. Bibcode:1993Natur.363...56S. doi:10.1038/363056a0.
  6. ^ Lee, Patrick A (2008). "From high temperature superconductivity to quantum spin liquid: progress in strong correlation physics". Reports on Progress in Physics. 71: 012501. arXiv:0708.2115. Bibcode:2008RPPh...71a2501L. doi:10.1088/0034-4885/71/1/012501.
  7. ^ Chu, C. W.; Gao, L.; Chen, F.; Huang, Z. J.; Meng, R. L.; Xue, Y. Y. (1993). "Superconductivity above 150 K in HgBa2Ca2Cu3O8+δ at high pressures". Nature. 365 (6444): 323. Bibcode:1993Natur.365..323C. doi:10.1038/365323a0.
  8. ^ "HTS materials for LHC current leads". CERN. November 23, 2005.