# 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 ${\textstyle {\ce {La_{2-x}Ba_{x}CuO_4}}}$. 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. 2005-11-23.