Effect of Pressure on the Pseudogap in Bi2223: Cuprates Are Not Strongly Coupled Superconductors
A. I. D’yachenko1, V. Yu. Tarenkov2, V. V. Kononenko2, E. M. Rudenko1
1G.V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky Blvd., UA-03680 Kyiv-142, Ukraine
2Donetsk Institute for Physics and Engineering Named after O.O. Galkin, NAS of Ukraine, 46 Nauky Ave., UA-03680 Kyiv, Ukraine
Received: 09.12.2015. Download: PDF
The Andreev and tunnelling spectroscopy methods show that hydrostatic pressure (P) enhances Tc with dln(Tc)/dP=(1,5±0,3)⋅10−3 kbar−1 and energy gap Δ0 with dln(Δ0)/dP=(4,5±0,5)⋅10−3 kbar−1 for the optimally doped Bi1.6Pb0.4Sr1.8Ca2.2Cu3Ox cuprate (Bi2223, Tc ≅ 110—112 К). The observed increase of ratio 2Δ0/(kTc) due to pressure is explained by the increase of the pseudogap ΔPG(dln(ΔPG)/dP=(4,5±0,5)⋅10−3 kbar−1), but not conditioned by increasing electron—boson coupling. The obtained results show that the anomalously large ratio 2Δ0/(kTc)≥8−9 for optimally doped cuprates is explained by the influence of the pseudogap, but not effective coupling of electrons with low-frequency bosons.
Key words: pseudogap, doped cuprates, energy gap, electron—boson coupling.
URL: http://mfint.imp.kiev.ua/en/abstract/v38/i05/0565.html
DOI: https://doi.org/10.15407/mfint.38.05.0565
PACS: 74.20.Fg, 74.25.Kc, 74.50.+r, 74.55.+v, 74.62.Fj, 74.72.-h, 74.72.Kf
Citation: A. I. D’yachenko, V. Yu. Tarenkov, V. V. Kononenko, and E. M. Rudenko, Effect of Pressure on the Pseudogap in Bi2223: Cuprates Are Not Strongly Coupled Superconductors, Metallofiz. Noveishie Tekhnol., 38, No. 5: 565—599 (2016) (in Russian)