Inelastic neutron scattering was used to study the Cu-O bond-stretching vibrations in optimally doped La 1.85Sr 0.15 CuO 4(T c = 35 K) and in two other cuprates showing static stripe order at low temperatures, i.e., La 1.48 Nd 0.4Sr 0.12CuO 4 and La 1.875 Ba 0.125CuO 4. All three compounds exhibit a very similar phonon anomaly, which is not predicted by conventional band theory. It is argued that the phonon anomaly reflects a coupling to charge inhomogeneities in the form of stripes, which remain dynamic in superconducting La 1.85Sr 0.15CuO 4 down to the lowest temperatures. These results show that the phonon effect indicating stripe formation is not restricted to a narrow region of the phase diagram around the so-called 1/8 anomaly but occurs in optimally doped samples as well.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Materials Science(all)
- Condensed Matter Physics