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High-Temperature Superconductors under pressure. NZIP2011 Ben Mallett Oct 2011
 
R. Hott  et al , Supercondcuting materials: A topical overview,  in “Frontiers in Superconducting Materials”, Springer-Ver...
Figure courtesy of S. Chong
Basic cuprate structure YBa 2 Cu 3 O 7-y
Figure courtesy of S. Chong
The phase diagram J.L. Tallon, Frontier in Superconducting Materials;  Oxygen in High-Tc Cuprate Superconductors , Springe...
Cu O The undoped cuprates are anti-ferromagnetic, charge transfer insulators d x 2 -y 2 2p σ a b
The phase diagram J.L. Tallon, Frontier in Superconducting Materials;  Oxygen in High-Tc Cuprate Superconductors , Springe...
Red triangles are external pressure measurement data reported by Wijngaarden  et al .,  Physica B ,  265 , 128-135 (1999)....
‘ Chemical’ or ‘Internal’ pressure Guillaume  et al.
Measuring Antiferromagnetic superexchange strength,  J , with Raman spectroscopy Two excited magnons
LnBa 2 Cu 3 O 6
La 2 CuO 4  data from - Aronson  et al .,  Phys. Rev. B ,  44 , 4657 (1991) YBa 2 Cu 3 O 6.2  pressure data from - Maksimo...
Red triangles are external pressure measurement data reported by Wijngaarden  et al .,  Physica B ,  265 , 128-135 (1999).
Other energy scales? <ul><li>Pseudogap – although believed to scale with  J … </li></ul><ul><li>Proximity to the van Hove ...
<ul><li>Dr. Jeff Tallon  </li></ul><ul><li>Dr. Grant Williams </li></ul><ul><li>Raman lab guys (VUW) </li></ul><ul><li>Mac...
<ul><li>External pressure; </li></ul><ul><li>Caveats; </li></ul><ul><ul><li>Doping dependent </li></ul></ul><ul><ul><li>Ch...
<ul><li>Caveats; </li></ul><ul><ul><li>Doping dependent </li></ul></ul><ul><ul><li>Charge transfer effects </li></ul></ul>...
 
Smaller ion size
Bi 2 Sr 1.6-y A y RE 0.4 CuO 6+z Caveat;  Likely to be additional effects influencing/suppressing Tc.
<ul><li>; Pairing boson energy scale </li></ul><ul><li>; Density of states at the fermi level – in the normal-state. </li>...
 
Hole dynamics a b Metal with residual AF correlations
The Fermi surface
 
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16.20 o11 b mallett

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16.20 o11 b mallett

  1. 1. High-Temperature Superconductors under pressure. NZIP2011 Ben Mallett Oct 2011
  2. 3. R. Hott et al , Supercondcuting materials: A topical overview, in “Frontiers in Superconducting Materials”, Springer-Verlag, 2004
  3. 4. Figure courtesy of S. Chong
  4. 5. Basic cuprate structure YBa 2 Cu 3 O 7-y
  5. 6. Figure courtesy of S. Chong
  6. 7. The phase diagram J.L. Tallon, Frontier in Superconducting Materials; Oxygen in High-Tc Cuprate Superconductors , Springer-Verlag, 2004. stripe phase
  7. 8. Cu O The undoped cuprates are anti-ferromagnetic, charge transfer insulators d x 2 -y 2 2p σ a b
  8. 9. The phase diagram J.L. Tallon, Frontier in Superconducting Materials; Oxygen in High-Tc Cuprate Superconductors , Springer-Verlag, 2004. stripe phase
  9. 10. Red triangles are external pressure measurement data reported by Wijngaarden et al ., Physica B , 265 , 128-135 (1999). LnBa 2 Cu 3 O 7-y
  10. 11. ‘ Chemical’ or ‘Internal’ pressure Guillaume et al.
  11. 12. Measuring Antiferromagnetic superexchange strength, J , with Raman spectroscopy Two excited magnons
  12. 13. LnBa 2 Cu 3 O 6
  13. 14. La 2 CuO 4 data from - Aronson et al ., Phys. Rev. B , 44 , 4657 (1991) YBa 2 Cu 3 O 6.2 pressure data from - Maksimov et al ., Phys. Rev. B , 49 , 15385, (1994)
  14. 15. Red triangles are external pressure measurement data reported by Wijngaarden et al ., Physica B , 265 , 128-135 (1999).
  15. 16. Other energy scales? <ul><li>Pseudogap – although believed to scale with J … </li></ul><ul><li>Proximity to the van Hove singularity in the Density of States. </li></ul><ul><li>Pairing potential, V . </li></ul><ul><li>Scattering rates. </li></ul>
  16. 17. <ul><li>Dr. Jeff Tallon </li></ul><ul><li>Dr. Grant Williams </li></ul><ul><li>Raman lab guys (VUW) </li></ul><ul><li>MacDiarmid Institute </li></ul><ul><li>Prof. Alan Kaiser </li></ul><ul><li>Prof. Thomas Wolf </li></ul>
  17. 18. <ul><li>External pressure; </li></ul><ul><li>Caveats; </li></ul><ul><ul><li>Doping dependent </li></ul></ul><ul><ul><li>Charge transfer effects </li></ul></ul><ul><ul><li>For lower pressures; </li></ul></ul><ul><ul><li>Anisotropic pressure may have different effect </li></ul></ul><ul><ul><li>… </li></ul></ul><ul><li>Caveats; </li></ul><ul><ul><li>Doping dependent </li></ul></ul><ul><ul><li>Charge transfer effects </li></ul></ul><ul><ul><li>For lower pressures; </li></ul></ul><ul><ul><li>Anisotropic pressure may have different effect </li></ul></ul><ul><ul><li>… </li></ul></ul>
  18. 19. <ul><li>Caveats; </li></ul><ul><ul><li>Doping dependent </li></ul></ul><ul><ul><li>Charge transfer effects </li></ul></ul><ul><ul><li>For lower pressures; </li></ul></ul><ul><ul><li>Anisotropic pressure may have different effect </li></ul></ul><ul><ul><li>… </li></ul></ul>
  19. 21. Smaller ion size
  20. 22. Bi 2 Sr 1.6-y A y RE 0.4 CuO 6+z Caveat; Likely to be additional effects influencing/suppressing Tc.
  21. 23. <ul><li>; Pairing boson energy scale </li></ul><ul><li>; Density of states at the fermi level – in the normal-state. </li></ul><ul><li>; Pairing potential </li></ul>
  22. 25. Hole dynamics a b Metal with residual AF correlations
  23. 26. The Fermi surface

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