High-TC superconductivity


High transition temperature superconductivity originates from the Coulombic interaction between two adjacent charge reservoirs; the type I reservoir hosts the superconducting condenstate with areal charge density σI/AI (per formula unit) while the type II reservoir contains the mediating charges (with an areal charge density of σII/AII). Given ν type I and η type II interacting component layers (interfaces), the optimal superconducting state is achieved when the two reservoirs are in equilibrium defined by [1],

νσI/AI = ησII/AII .

Validation of this equation can be found, e.g., in the charge-compensated cuprate, (Ca0.45La0.55)(Ba1.3La0.7)Cu3Oy (where ν = η = 2 and AAII). Owing to the energies involved, the optimal transition temperature TC0 is independent of band structure, determined completely by the interacting charge density and the separation between the two reservoirs according to the algebraic expression [1],

TC0 = kB−1 β (ση/A)1/2 ζ−1 ,

where ζ is the interaction distance (along the transverse axis), σ/A (=σI/AI) is the optimal areal charge density per type I layer per formula unit for participating charges, η is the number of mediating layers (e.g., the number of cuprate planes), and β (= 0.1075 ± 0.0003 eV Å2) is a universal constant; e–2β is approximately twice the reduced electron Compton wavelength. Rules for determining σ are discussed here (see also, notes), and the relevant experimental parameters and the calculated values of TC0 are listed under Tabulated results for 50 optimal high-TC materials from seven superconductor families. This pairing interaction model was first introduced in 2011 [1]. and has since been further developed and expanded by Dale R. Harshman and Anthony T. Fiory [2-8].

  1. D. R. Harshman, A. T. Fiory and J. D. Dow, J. Phys.: Condens. Matter 23, 295701 (2011)23 349501 (2011).
  2. D. R. Harshman and A. T. Fiory, J. Phys.: Condens. Matter 24, 135701 (2012).
  3. D. R. Harshman and A. T. Fiory, Phys. Rev. B 86, 144533 (2012).
  4. D. R. Harshman and A. T. Fiory, J. Phys. Chem. Solids 85, 106 (2015).
  5. D. R. Harshman and A. T. Fiory, Phys. Rev. B 90, 186501 (2014).
  6. D. R. Harshman and A. T. Fiory, J. Supercond. Nov. Magn. 28, 2967 (2015).
  7. D. R. Harshman and A. T. Fiory, J. Phys.: Condens. Matter 29, 145602 (2017).
  8. D. R. Harshman and A. T. Fiory, J. Phys.: Condens. Matter 29, 445702 (2017).

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