Coexistence of, and Competition between, Superconductivity and Charge-Stripe Order inLa1.6−xNd0.4

Abstract

Previously we have presented evidence for stripe order of holes and spins in La1.6−xNd0.4SrxCuO4 with x = 0.12. Here we show, via neutron diffraction measurements of magnetic scattering, that similar order occurs in crystals with x = 0.15 and 0.20. Zero-field-cooled magnetization measurements show that all 3 compositions are also superconducting, with the superconducting transition temperature increasing as the low-temperature staggered magnetization decreases. 74.72.Dn,71.45.Lr,75.50.Ee,75.70.Kw Neutron scattering studies [1,2,3,4,5,6,7] of dynamical magnetic correlations in superconducting La 2−x Sr x CuO 4 have provided important clues to the nature of electronic correlations within the doped CuO 2 planes. The lowenergy magnetic scattering, which is characterized by the two-dimensional antiferromagnetic wavevector Q AF = ( [7]. In one common interpretation [8,9,10,11], the incommensurate peaks are viewed as the dynamical response of a spatially uniform electron liquid with a nearly-nested Fermi surface. From a rather different perspective, the Q-dependent structure is taken as evidence for spatial inhomogeneity associated with charge segregation [12,13,14] or charge-density-wave correlations [15,16,17,18]. Evidence for the latter picture is provided by our recent discovery [19,20] of incommensurate charge and spin order in La 1.6−x Nd 0.4 Sr x CuO 4 with x = 0.12; however, given the claim [21] that bulk superconductivity is absent at this composition, one might choose to argue that these results are not directly relevant to the case of superconducting samples.To test the relationship between charge-stripe order and superconductivity, we have now investigated two other Sr concentrations, x = 0.15 and 0.20. Our neutron diffraction measurements on single-crystal samples reveal elastic incommensurate magnetic peaks for both compositions, thus demonstrating the presence of chargestripe order. Since the x = 0.20 crystal was known to be superconducting from previous work [22], we decided to check the x = 0.12 and 0.15 crystals for superconductivity as well. To our surprise, zero-field-cooled susceptibility measurements exhibit a bulk shielding signal for all three compositions. Since both the incommensurate peak splitting, ǫ, and the superconducting transition temperature vary with x, the results strongly suggest a local coexistence of superconductivity and stripe order. The fact that T c decreases as the staggered magnetization increases indicates that these two types of order compete with one another [23]. Furthermore, since the variation of ǫ with x in the Nd-doped crystals is essentially identical to that obtained from recent inelastic measurements [7] on crystals of La 2−x Sr x CuO 4 , it seems inescapable that dynamical charge-stripe correlations are present in the optimally doped material.The crystals studied in this work were grown at the University of Tokyo using the traveling-solvent floatingzone method. The transport properties of the x = 0.12 and 0.20 compositions were reported several years ago [22...

Stripe order in superconducting La2−xBaxCuOHücker1, Zimmermann2, Gu3 et al. 2011Phys. Rev. BSelf Cite304434112View full textAdd to dashboardCite

“…This is in contrast to the observations in La 1.6−x Nd 0.4 Sr x CuO 4 with nominal x = 0.12 and 0.125, where the measured δ values are closer to the expected trend, and for x = 0.15 even exceed the 1/8 mark. 13,14,20,49,62 These quantitative differences need further experimental clarification. In terms of the simple stripe picture one may speculate that in La 2−x Ba x CuO 4 with x 1/8 the hole concentration of the charge stripes is slightly higher than expected, or that not all doped holes participate in the CO, or at least less than in La 1.6−x Nd 0.4 Sr x CuO 4 with identical x.…”

Fermi surface and spectral functions of a hole-doped spin-fermion model for cuprates

“…[1] In some compounds it is believed that this spin IC is due to the formation of charge stripes. [2] Indirect evidence of static stripes formation has been observed in Nd doped La 2−x Sr x CuO 2 (LSCO). [2] On the other hand, in LSCO, angular resolved photoemission experiments (ARPES) [3] as well as neutron scattering [4], show features consistent with the existence of dynamical stripes.…”

“…[2] Indirect evidence of static stripes formation has been observed in Nd doped La 2−x Sr x CuO 2 (LSCO). [2] On the other hand, in LSCO, angular resolved photoemission experiments (ARPES) [3] as well as neutron scattering [4], show features consistent with the existence of dynamical stripes. In neutron scattering the evidence is in the broadening of the peak in the supposedly inhomogeneous stripe regime, while in ARPES a one-dimensional-like band dispersion and a straight Fermi surface (FS) around (π, 0) and (0, π) are observed.…”

Magnetic excitation spectrum of the square latticeS=1∕2Heisenberg antiferromagnetK2VLumsden1, Nagler2, Sales3 et al. 2006Phys. Rev. B210260View full textAdd to dashboardCite

“…The effects of periodic modulations of exchange interactions has received some attention in recent years in investigating the effects of stripe order on the magnetic interactions in cuprates. [75][76][77] A recent theoretical investigation described the modification of the Hamiltonian required to account for such an exchange constant modulation in the limit of weak modulation strength. 78 This study suggests that simple model systems, for instance, conventional antiferromagnets such as K 2 V 3 O 8 , would be insensitive to small long-wavelength modulations of the exchange constants.…”