139La NMR investigation of the charge and spin order in a La1.885Sr0.115CuO4 single crystal

La-139 NMR is suited for investigations into magnetic properties of La2CuO4-based cuprates in the vicinity of their magnetic instabilities, owing to the modest hyperfine interactions between La-139 nuclear spins and Cu electron spins. We report comprehensive La-139 NMR measurements on a single-crystal sample of high-T-c superconductor La1.885Sr0.115CuO4 in a broad temperature range across the charge and spin order transitions (T-charge similar or equal to 80 K, T-spin(neutron) similar or equal to T-c = 30 K). From the high-precision measurements of the linewidth for the nuclear spin I-z = +1/2 to -1/2 central transition, we show that paramagnetic line broadening sets in precisely at T-charge due to enhanced spin correlations within the CuO2 planes. Additional paramagnetic line broadening ensues below similar to 35 K, signaling that Cu spins in some segments of CuO2 planes are on the verge of three-dimensional magnetic order. A static hyperfine magnetic field arising from ordered Cu moments along the ab plane, however, begins to develop only below T-spin(mu SR) = 15-20 K, where earlier muon spin rotation measurements detected Larmor precession for a small volume fraction (similar to 20%) of the sample. Based on the measurement of La-139 nuclear-spin-lattice relaxation rate 1/T-1, we also show that charge order triggers enhancement of low-frequency Cu spin fluctuations inhomogeneously; a growing fraction of La-139 sites is affected by enhanced low-frequency spin fluctuations toward the eventual magnetic order, whereas a diminishing fraction continues to exhibit a behavior analogous to the optimally superconducting phase even below T-charge. These La-139 NMR results corroborate our recent Cu-63 NMR observation that a very broad, anomalous winglike signal gradually emerges below T-charge, whereas the normally behaving, narrower main peak is gradually wiped out [T. Imai et al., Phys. Rev. B 96, 224508 (2017)]. Furthermore, we show that the enhancement of low-energy spin excitations in the low-temperature regime below T-spin(neutron) (similar or equal to T-c) depends strongly on the magnitude and orientation of the applied magnetic field.