Effect of praseodymium on the electrical resistance of YВа2Сu3О7−δ single crystals

Effect of defects on the basal-plane resistivity of $$\hbox {YBa}_2\hbox {Cu}_3\hbox {O}_{7-\delta }$$ YBa 2 Cu 3 O 7 - δ and $$\hbox {Y}_{1-y}\hbox {Pr}_y\hbox {Ba}_2\hbox {Cu}_3\hbox {O}_{7-x}$$ Y 1 - y Pr y Ba 2 Cu 3 O 7 - x single crystals

“…The [46] reported are data on the correlation between T c and k for 12 transition metals, whereby k is calculated by using the McMillan formula (3) for l à ¼ 0:13. Figure 4 presents these data alongside with the analogous ones for YBa 2 Cu 3 O 7Àd (see Table 1) and Y 1Ày Pr y Ba 2 Cu 3 O 7Àx [25]. One sees that only for T c 65 K the data for transition metals agree with the data for YBa 2 Cu 3 O 7Àd and Y 1Ày Pr y Ba 2 Cu 3 O 7Àx , thereby attesting to a strong electronphonon interaction in these compounds.…”

“…In addition to this, measurements of non-twinned samples would give information on the presence (or absence) of the step-like form of the superconducting transition in the absence of planar disorder in the sample. Figure 2 presents the dependence T c ðdÞ (curve 1, after [7]) and the dependence of T c on the praseodymium concentration index y for Y 1Ày Pr y Ba 2 Cu 3 O 7Àx single crystals (curve 2, after [25]). One sees that these dependences are very similar, especially for y; d 0:2.…”

“…One sees that these dependences are very similar, especially for y; d 0:2. The dependence T c ðyÞ can be approximated by the universal Abrikosov-Gorkov equation describing the suppression of T c by non-magnetic defects in the case of d-pairing [25,[35][36][37]. For the dependence T c ðdÞ one of the models [38] assumes a random distribution of vacancies in the Cu(1)-O(1) chains.…”

“…The YBa 2 Cu 3 O 7Àd and Y 1Ày Pr y Ba 2 Cu 3 O 7Àx single crystals were grown by the solution-melt technique in a gold crucible at temperatures 850-970 C as detailed in [10,23,25]. To obtain samples with the optimal oxygen content, the crystals were annealed in an oxygen atmosphere at 400 C for 5 days.…”

“…As is well known [21][22][23], substituting yttrium with other rare earths affects the electro-transport parameters of the compound YBa 2 Cu 3 O 7Àd only slightly. The exception from this is a partial or full substitution of yttrium with praseodymium, the so-called ''praseodymium anomaly'' [24,25]. Previously [25], we investigated the effect of praseodymium doping on the basal-plane resistivity of optimally oxygen-doped Pr-Y-Ba-Cu-O single crystals and observed a significant influence of Pr on the characteristics of the charge transfer and scattering of its carriers.…”