Multilayer effects in Bi₂Sr₂Ca₂Cu₃O_10+z superconductors

Abstract

We discuss the characteristic features of triple Cu-O2 layer cuprates superconductors, by comparing those of single and double layer cuprates superconductors. After a brief introduction to multilayer cuprates and their characteristic properties such as the doping imbalance between the inner and outer Cu-O2 planes (IP and OP, respectively) revealed by nuclear magnetic resonance, we present the experimental results of angle resolved photoemission and Raman scattering spectroscopy for the triple layer Bi2Sr2Ca2Cu3O10+z which showed two different superconducting gaps opening on the IP and OP.The doping dependence of the double peak structure in Raman spectra was found to be qualitatively consistent with that of single and double layer cuprates, if each layer doping for the IP and OP is taken into account. The fact that the IP and OP share the same electronic phase diagram and the same transition temperature (Tc) hints to a coupling between the IP and OP. Moreover, the energies of IP and OP Raman peaks were found to be very large, not scaling with Tc, which can be attributed to the strong influence of the pseudogap of the underdoped IP in triple layer cuprates. These findings suggest that the high Tc and the large gap ratio of triple layer cuprates are realized through a combination of the interlayer coupling between the OP and IP and the interaction between superconductivity and the pseudogap.

Gapped Collective Charge Excitations and Interlayer Hopping in Cuprate Superconductors

“…In particular, it should be evaluated whether the gap energy has a positive or negative effect in the suggested pairing scenarios. Along the lines of previous discussions about a correlation between T c and the magnitude of t [74], future applications of our methodology may provide new insights into a possible relation between T c and t z , as well as the putative scaling of T c with the number of CuO 2 planes per unit cell [75,76]. In this context, we note that the large-N theory for the t-J-V model indicates that the doping-dependence of the plasmon gap exhibits a domelike shape [47], similar to the T c dome of cuprates [1].…”

Nano-scale periodic structures and gap distribution in Pb-doped Bi2223 cuprate superconductors observed by STM/STS

“…The Bi-based high-critical temperature (T c ) superconducting oxides (Bi 2 Sr 2 Ca n − 1 Cu n O 2n + 4 + y ; Bi22(n-1)n, n = 1, 2, 3) remain one of the most fascinating families among other cuprate superconductors because of their high T c which exceeds 100 K (max. T c ∼ 110 K at n = 3) and interesting concomitant features changing with the varying number (n = 1, 2, 3) of the CuO 2 planes [1][2][3]. Furthermore, they demonstrate easy cleavability with clean and chargeneutral surface of BiO surfaces.…”

Renormalization of electrons in bilayer cuprate superconductors

“…In particular, the strongly correlated motion of the electrons confined to the copper-oxide layers has been confirmed experimentally by the incoherent charge-transport along the outof-copper-oxide layer direction [18][19][20][21] . However, the exotic properties are significantly enriched by the coupling between the copper-oxide layers when two or more two copper-oxide layers are contained in a unit cell [22][23][24][25][26][27][28][29][30][31] . For instance, T c is very sensitive to the number of the copperoxide layers n within a unit cell [22][23][24][25][26][27][28][29][30][31] , i.e., for all families of cuprate superconductors, the magnitude of the optimized T c is found experimentally to increase with the increase of n per unit cell for the case of n < 3, and reaches the maximum for the case of n = 3, then decreases slightly and saturates for the case of n > 3, which therefore shows clearly that the number of the copper-oxide layers dependence of the optimized T c is induced by the coupling between the copper-oxide layers within a unit cell.…”