High-resolution neutron spectroscopy of La1.855Sr0.145CuO4

Data from a high-resolution neutron spectroscopy investigation of the low-energy incommensurate spin excitations in the high-temperature superconductor La1.855Sr0.145CuO4. The study was conducted using the IN5 time-of-flight neutron spectrometer at the Institut Laue-Langevin. The sample consisted of two crystals with a combined mass of 3.5 g and a superconducting transition temperature of 36 K. These crystals were prepared from a single rod grown via the traveling-solvent floating-zone method and aligned within a deviation of less than a degree. The lattice parameters are a = b = 3.81 Å and c = 13.2 Å, in the notation of the high-temperature tetragonal unit cell. Measurements were performed on the sample in a standard cryostat.  Magnetic excitation spectra were acquired with a fixed sample orientation (b-axis perpendicular to the horizontal scattering plane) over 12 or 24 hours at various temperatures. Two distinct experimental configurations were utilized, employing incident wavelengths λ_i = 3.3 Å and 5 Å. The shorter wavelength was used to validate the magnitude of the superconducting spin gap (4 meV) at a base temperature of T = 2 K. The λ = 5 Å setup was employed to gather spectra at temperatures of T = 40, 30, 25, and 20 K, with an elastic full-width at half maximum resolution of ΔE = 80 μeV.