High-energy magnetic excitations from dynamic stripes inLa1.875Ba0.125CuO4

Abstract

We use inelastic neutron scattering to study the temperature dependence of magnetic excitations (for energies up to 100 meV) in the cuprate La1.875Ba0.125CuO4. This compound exhibits stripe order below a temperature of ∼50 K; previous measurements have shown that the magnetic excitations of the stripe-ordered phase have an hour-glass-like dispersion, with a saddle point at ∼ 50 meV. Here we compare measurements in the disordered phase taken at 65 and 300 K. At energies on the scale of kBT , there is substantial momentum-broadening of the signal, and the low-energy incommensurate features can no longer be resolved at 300 K. In contrast, there is remarkably little change in the scattered signal for energies greater than kBT . In fact, the momentum-integrated dynamic susceptibility is almost constant with temperature. We suggest that the continuity of higher-energy magnetic excitations is strong evidence for dynamic stripes in the high-temperature, disordered phase. We reconsider the nature of the magnetic dispersion, and we discuss the correspondences between the thermal evolution of magnetic stripe correlations with other electronic properties of the cuprates.

Quantum spin excitations through the metal-to-insulator crossover inYBa2Cu3O6+y

“…Indeed, such speculation is also consistent with the data in LSCO, where one finds a clean spin gap and incommensurate "resonance" -or more precisely, susceptibility gain below T c -near optimal Sr-doping in the metallic phase 12,13,38 but fails to detect any signature of a clean spin gap or resonance in underdoped materials in the insulating-like phase 17,18,39 .…”

“…Neutron scattering experiments on La 1.875 Ba 0.125 CuO 4 , where superconductivity is suppressed by the static stripes, have shown that spin excitations form an hourglass dispersion (Fig. 7d) with low-energy incommensurate peaks (measuring spacing between stripes) merge into a saddle point determined by the interactions between stripes 17,18 . In this picture, incommensurate spin excitations in the superconducting LSCO and YBCO arise from dynamic stripes 5 and the MIC itself is not expected to much affect the stripe correlations 40,41 .…”

“…For deeply underdoped YBa 2 Cu 3 O 6.353 (T c = 18 K), the spin excitations spectra become gapless and resonance-less; however, they are dominated by commensurate spin excitations and a central diffusive mode associated with a spin-glass phase 14,15,16 . On the other hand, spin excitations in the underdoped La 1.875 Ba 0.125 CuO 4 are also gapless and resonance-less but display an hourglass dispersion with incommensurate scattering extending to zero energy 5,17,18 . For underdoped superconducting LSCO (0.055 ≤ x ≤ 0.125), spin excitations have clear incommensurability down to the lowest doping of 0.055 and behave similarly as those for La 1.875 Ba 0.125 CuO 4 19 .…”

Spins, stripes, and superconductivity in hole-doped cuprates

“…The righthand side of Fig. 42 presents an approximate version of the experimental S (Q, ω) for magnetic excitations in La 1.875 Ba 0.125 CuO 4 [72,82]. As one can see, there is a lot of weight near E cross ∼ 50 meV.…”

Stripe order in superconducting La2−xBaxCuOHücker1, Zimmermann2, Gu3 et al. 2011Phys. Rev. BSelf Cite297434092View full textAdd to dashboardCite

“…39,40 Recent progress in the synthesis of La 2−x Ba x CuO 4 single crystals with x ≤ 1/8 has triggered numerous studies on the stripe order in the underdoped regime. [18][19][20][41][42][43][44][45][46][47][48][49][50] Despite previous work, however, the doping dependence of many properties requires further clarification, such as the absolute intensities of CO and SO satellite reflections, the stripe correlations between the planes, the melting of the stripe order, and the compatibility with the generic stripe phase diagram. Furthermore, there is a great lack of information for x > 1/8 because crystal growth becomes progressively more challenging with increasing x.…”