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Structural and electronic properties of YBa2Cu3O 7 and YSr2Cu3O7 under mechanical and strontium chemical pressures

Khosroabadi, H ; Sharif University of Technology | 2004

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  1. Type of Document: Article
  2. DOI: 10.1103/PhysRevB.70.134509
  3. Publisher: 2004
  4. Abstract:
  5. Calculations of structural and electronic properties of two YBa 2Cu3O7 (YBCO) and YSr2Cu 3O7 (YSCO) high-Tc cuprate isofamilies for ambient and high mechanical pressures (-15 GPa≤pm≤15 GPa) have been carried out by pseudopotential density functional theory in the local density approximation employing VASP code. We have analyzed the changes of bond lengths and equilibrium ionic positions due to mechanical pressure on YBCO and YSCO. Negative pressure causes separation of the YBCO unit cell into Cu(1)-O(1)-O(4) and CuO2-Y-CuO2 blocks, similar to the effect of oxygen reduction in YBCO. We have also found that the nonlinear dependence for ionic positions by mechanical pressure, especially for Cu(2), O(4), O(3), and O(2) ions, causes the redistribution of charge density and the transfer of hole to the CuO2 planes and CuO chains for both systems. It is concluded that in spite of the larger dTc/dpm for YSCO in comparison with YBCO, the charge transfer in YSCO is lower than in YBCO. This apparent discrepancy has been discussed on the basis of the effect of oxygen on dTc/dpm and the pressure-induced charge-transfer model. Different structural changes due to mechanical and Sr chemical pressures have been discussed for their opposite effects on Tc. Compressibility and equilibrium unit-cell volume for both systems have also been obtained and compared with experimental and computational reports
  6. Keywords:
  7. Copper derivative ; Structure analysis ; Density functional theory ; Nonlinear system
  8. Source: Physical Review B - Condensed Matter and Materials Physics ; Volume 70, Issue 13 , 2004 , Pages 134509-1-134509-9 ; 01631829 (ISSN)
  9. URL: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.70.134509