Copper and oxygen isotope effects inLa2−xSr

Unconventional isotope effects in the high-temperature cuprate superconductors

“…Several groups [21,22] noticed that there is an isotope effect on the diamagnetic Meissner signal in decoupled fine-grained samples. Zhao et al [25] carefully studied this effect and interpreted it as due to the isotope-mass dependence of the average supercarrier mass m * * (≡ 3 (m * * ab ) 2 m * * c ).…”

“…The small OIS observed in the optimally doped cuprates suggest that phonons might not be important in bringing about high temperature superconductivity. However, the doping dependence of the OIS has been extensively studied in different cuprate systems [17,[20][21][22][23][24][25][26][27]. For a particular family of doped cuprates the OIS increases with decreasing T c , and can be even larger than the BCS value.…”

Prerequisite for superconductivity: Appropriate spin-charge correlations

“…The "increased spin-charge correlation" is related to the increased charge-charge correlation. Thirdly, the Fourthly, the unusual isotope effects (on c T ) in optimally doped cuprates can be understood [15], because the strong correlation may dominate the superconductivity in this region. As discussed above, a higher c T is due to the higher A S .…”

Large oxygen-isotope effect inSr0.4K0.6BiO3Zhao1, Conder2, Angst3 et al. 2000Phys. Rev. B5030View full textAdd to dashboardCite

“…If this were the case, the isotope effects in both cuprates and bismuthates would be similar. As a matter of fact, the oxygen-isotope exponent α O in BKBO has a maximum at optimal doping where T c is the highest [8], while α O in optimally-doped cuprates is the smallest [9][10][11][12]. Moreover, the isovalent substitution of Ca for Sr in the single-layer La 2−x Sr x CuO 4 system leads to a large decrease in T c , and to a large increase in α O [13].…”

“…[6,8], and the data for the cuprates are taken from Ref. [10,15]. The data for Sr 1−x K x BiO 3 (T c = 12 K) are from this work.…”