Spontaneous Symmetry Breaking by Charge Stripes in the High Pressure Phase of SuperconductingLa1.875Ba0.125CuO4

Abstract

In those cases where charge-stripe order has been observed in cuprates, the crystal structure is such that the average rotational symmetry of the CuO2 planes is reduced from fourfold to twofold. As a result, one could argue that the reduced lattice symmetry is essential to the existence of stripe order. We use pressure to restore the average fourfold symmetry in a single crystal of La1.875Ba0.125CuO4, and show by x-ray diffraction that charge-stripe order still occurs. Thus, electronically driven stripe order can spontaneously break the lattice symmetry.

Stripe order in superconducting La2−xBaxCuOHücker1, Zimmermann2, Gu3 et al. 2011Phys. Rev. BSelf Cite303434112View full textAdd to dashboardCite

“…Previously reported results on some of the compositions, in particular on the x = 1/8 crystal, have demonstrated a very high sample quality. 20,[34][35][36]44,[51][52][53][54][55] Since the compositions of the single crystals can deviate from their nominal stoichiometry (see Ref. 56), it has been vital to measure the structure, stripe order, and SC on pieces of the same crystal.…”

“…However, in our recent high pressure experiments on La 2−x Ba x CuO 4 at x = 1/8 we have found that static charge stripes form even for Φ = 0, where the average structure has flat CuO 2 planes. 34 We believe that in this latter case the interactions between dynamic short range charge stripe correlations and local octahedral tilts trigger a spontaneous symmetry breaking by stripes. This mechanism may be particularly strong for commensurate x = 1/8 doping.…”

“…12,[26][27][28] In the LTT phase, which breaks the fourfold rotational symmetry of the individual CuO 2 planes, the electron-lattice coupling is believed to play a central role in the pinning of stripes, [29][30][31][32][33] although recent experiments under pressure revealed that stripes can break the symmetry even in the absence of long range LTT order. 34 So far, La 1.6−x Nd 0.4 Sr x CuO 4 is the only system with stripe-ordered LTT phase where magnetic and charge order have been studied with diffraction on both sides of x = 1/8. 15 The results were interpreted as indicating that local magnetic order (rather than charge stripe order) is responsible for the suppression of bulk SC, and that charge stripes are compatible with SC as long as the magnetic correlations remain dynamic.…”

High pressure neutron and X-ray diffraction at low temperatures

“…This process can be lengthy, and may introduce systematic error to the experiment. This cell has been used for studies of weak superstructures in transition metal oxides [113] on a triple-axis spectrometer. The cell is particularly well suited to small angle studies, due to the size of the thinned aperture and the optimum energy of the incident beam.…”

Inhomogeneous Electronic Distribution in High-Tc Cuprates

“…[6][7][8][9][10][11][12] The stripe order has also been observed by x-ray scattering. [12][13][14][15][16][17] Furthermore, an electron paramagnetic resonance study showed that micro-scopic electronic phase separation occurs in La 2−x Sr x Cu 0.98 Mn 0.02 O 4 with 0.01 ≤ x ≤ 0.06, 18 and a Cu nuclear magnetic resonance (NMR) study suggested that a large charge droplet ('blob') is formed in the electron-doped Nd 1.85 Ce 0.15 CuO 4−δ . 19 Much theoretical works has also been performed to study the behavior of the doped carriers in HTSC.…”