The systematic study of the normal-state transport properties of Bi-2212 crystals

Abstract

The temperature dependences of the in-plane resistivity ab(T ) and out-of-plane resistivity c(T ) in Bi-2212 crystals covering the region from the underdoped to the overdoped regime have been measured. In the underdoped regime, ab(T ) deviates from a linear temperature dependence below a characteristic temperature T *, well above Tc, whose value decreases with increasing hole concentration. For underdoped crystals, ab(T) shows a typical S-shaped temperature dependence and ab = 0*+exp(-/T ) is satisfactorily obeyed over a much wider temperature range from slightly above Tc up to T *. Near the optimal region, the T -linear dependence of ab(T ) is maintained over a wide temperature interval. In contrast, a power law ab~Tn (n = 1.5-1.8) is followed in the overdoped regime. As regards the out-of-plane resistivity, on the other hand, c(T ) for the underdoped Bi2Sr2CaCu2Oy crystals shows a semiconductive behaviour, which is well described by the formula c = (C1/T)exp(C2/T ) + C3T + C4. The difference between the temperature dependences of c(T ) in the overdoped Bi2Sr2CaCu2Oy and Bi1.85Pb0.15Sr2CaCu2O8 + crystals, with basically the same values of Tc and nearly the same power-law temperature dependences of ab(T ) (ab~T 1.4), reveals that the inter-plane disorder in the form of oxygen vacancies and substituted cations acting as an extra blocking layer plays an important role in out-of-plane transport.

Pseudogap and conduction dimensionalities in high-Tc superconductors

“…9 above T * as shown with ✷ lacks the T -linear metallic behavior if observed closely and also give ∆P G = −57 K. Leridon et al [11] B2, Carrington et al [11] Eq. ( 15) and ( 16) ρ ab (mΩ.cm) D4, Ruan et al [12] C3, Ruan et al [12] Eq. ( 15) and ( 16) Eq.…”

“…Thus, 2D ∆ P G in c-axis normal state conduction that could be thought of as a function of doping, be it ionic substitution or oxygen content, extends to ab-planes and becomes 3D due to increasing ∆ P G with decreasing oxygen content or certain ionic substitution. Such properties in Y123 [11] and Bi2212 [12] samples with different oxygen content (7−δ) and Ca 2+…”

Mapping of Structural Changes Induced by X-ray Nanopatterning via Nano-X-ray Diffraction and Corresponding Electrical Effects

“…42 In this context, the minimum T c observed has been T c ≈ 35 K, corresponding to y = 0.42 and to a room-temperature resistivity ρ ≈ 20 × 10 −6 Ω m. Similar results (T c ≈ 50 K and ρ ≈ 30 × 10 −6 Ω m at room temperature) have been obtained by a parallel systematic study. 41 Although we have not performed a systematic study as a function of CD and CF so far, a preliminary comparison between the Bi-2212 properties emerging from our heaviest irradiation conditions (i.e., T c ≈ 48 K and ρ ≈ 64 × 10 −6 Ω m, see also Figure S5 in the Supporting Information) and the ones obtained by means of cation substitution shows that the UD status induced in our case substantially preserves the same value of T c even if the normal-state resistivity is larger by at least a factor of 2. This observation seems to suggest that, given the same level of normal-state resistivity ρ, the Bi-2212 underdoping process via irradiation preserves the superconducting properties more than cation substitution.…”

“…More often, UD crystals have been obtained by means of a postannealing stage with very low oxygen partial pressure (or vacuum). Typically, these procedures result in only moderately UD samples with T c ≥ 65 K. ,, This is the reason why the partial substitution of 3+ valence atoms for 2+ cations (e.g., Bi 3+ for Sr 2+ , or Y 3+ for Ca 2+ ) has been tried several times to induce arbitrary small doping regimes. − By means of this technique, it has been possible to systematically explore the full doping range of Bi 2 Sr 2 Ca 1– y Y y Cu 2 O 8 from OD to UD all the way down to the insulating behavior, detecting the metal–insulator transition at y = 0.45 . In this context, the minimum T c observed has been T c ≈ 35 K, corresponding to y = 0.42 and to a room-temperature resistivity ρ ≈ 20 × 10 –6 Ω m. Similar results ( T c ≈ 50 K and ρ ≈ 30 × 10 –6 Ω m at room temperature) have been obtained by a parallel systematic study .…”

Comparative Study of the Effects of La-Substituted Ca in (Bi, Pb):2212 and (Bi, Pb):2223 Superconductors

“…It was found that the critical concentration x c of La for quenching superconductivity can be extended above 0.30 for both series, which is higher than that reported (0.25). [8][9][10][11][12][13][14][15][16][18][19][20][21][22]26,52,53 It was also clear that La slightly had a higher solubility in the 2212 series, and it was less detrimental to the superconductivity as compared to the 2223 series; that is [T c (x)/T c (0)] α (1/T c ) for BSCCO systems.…”