Stripe correlations of spins and holes and phonon heat transport in doped La ₂ CuO ₄

Abstract

We present experimental evidence for a dramatic suppression of the phononic thermal conductivity of rare earth and Sr doped La 2 CuO 4 . Remarkably, this suppression correlates with the occurrence of superconductivity. Conventional models for the phonon heat transport fail to explain these results. In contrast, a straightforward explanation is possible in terms of static and dynamic stripe correlations of holes and spins. PACS: 72.15.Eb Electrical and thermal conduction in crystalline metals and alloys 74.62.Dh Effects of crystal defects, doping and substitution 74.72.Dn La-based cuprates Typeset using REVT E X

Heat transport ofLa2−yEuyCuO

“…Eu-doping in this LSCO system significantly increases the low-T phononic thermal conductivity; clear phonon peak reappears in both κ ab and κ c . Similar behavior in R-doped LSCO was first attributed by Baberski et al 22 to the weakening of phonon scattering in the static stripe phase. However, their data were collected on polycrys- 12 CuO 4 has stronger phonon scattering (which may come from Eu dopants) at high temperatures even in the LTT phase.…”

“…20 Interestingly, it was found that in R-doped LSCO, such as La 1.28 Nd 0.6 Sr 0.12 CuO 4 , the low-T thermal conductivity is much enhanced in the non-superconducting LTT phase, compared to that in LSCO with the same Sr content. 22 This cannot happen if the defect scattering and electron scattering of phonons are the only source of the phonon peak suppression in LSCO. Alternatively, it was proposed that the strong suppression of phonon heat transport in LSCO is due to the strong phonon scattering by the structural distortion associated with the dynamical stripes, while R-doping leads to the formation of static stripes that significantly reduces the phonon scattering.…”

“…Alternatively, it was proposed that the strong suppression of phonon heat transport in LSCO is due to the strong phonon scattering by the structural distortion associated with the dynamical stripes, while R-doping leads to the formation of static stripes that significantly reduces the phonon scattering. 22 However, this supposition would be too straightforward, because the low-T structure phases are LTO and LTT in LSCO and R-doped LSCO, respectively, which possess different phonon spectra and phonon scattering. In fact, it has already been reported that the structural symmetry does affect the phonon properties; for example, the sound velocities in the three structures are known to be v s (LTT) > v s (LTO2) > v s (LTO), 23 which implies that the phononic thermal conductivity is likely the largest in the LTT phase and the smallest in the LTO phase.…”

Flux phase as a dynamic Jahn-Teller phase: Berryonic matter in the cuprates

“…Typically, κ is suppressed above the transition due to collisions between phonons and fluctuating stripes. Baberski, et al 114 find a very similar suppression of κ in the cuprates, but always at the LTT transition. Figure 14 compares the thermal conductivity near the LTT transition in LSCO:Nd [ 114] (b) with that of the charge ordering transition in a manganite 115 (a), suggesting an intimate connection between the LTT and charge ordering transitions.…”

“…Baberski, et al 114 find a very similar suppression of κ in the cuprates, but always at the LTT transition. Figure 14 compares the thermal conductivity near the LTT transition in LSCO:Nd [ 114] (b) with that of the charge ordering transition in a manganite 115 (a), suggesting an intimate connection between the LTT and charge ordering transitions. In the absence of long range LTT order, κ is suppressed over the full temperature rangethis is found both for pure LSCO and for the RE substituted materials, for x > 0.17.…”