Stripe order, depinning, and fluctuations in La$_{1.875}$Ba$_{0.125}$CuO$_{4}$ and La$_{1.875}$Ba$_{0.075}$Sr$_{0.050}$CuO$_{4}$

摘要: We present a neutron scattering study of stripe correlations measured on single crystal La$_{1.875}$Ba$_{0.125}$CuO$_{4}$. Within the low-temperature-tetragonal (LTT) phase, superlattice peaks indicative spin and charge order are observed below 50 K. For excitation energies $\hbar\omega\le12$ meV, we have characterized magnetic excitations that emerge from incommensurate peaks. In ordered state, these similar to waves. Following as function temperature, find there is relatively little change in {\bf Q}-integrated dynamical susceptibility for $\hbar\omega\sim10$ meV disappears then structure transforms LTT low-temperature-orthorhombic (LTO) phase. The signal at lower changes more dramatically through transitions, it must transformation an disordered state. argue continuous evolution transitions provides direct evidence state indicator stripes. An interesting feature thermal variation incommensurability scattering. Similar behavior measurements La$_{1.875}$Ba$_{0.075}$Sr$_{0.050}$CuO$_{4}$; maps scattered intensity region centered antiferromagnetic wave vector $\hbar\omega=4$ well reproduced by model stripes with temperature-dependent mixture spacings. discuss relevance our results understanding cuprate superconductors.