Neutron-scattering study on spin fluctuations in high-temperature-tetragonal phase of La1.70Sr0.24Ce0.06CuO4

We investigated spin fluctuations in the high-temperature-tetragonal phase of La1.70Sr0.24Ce0.06CuO4. At 8 K, well-defined incommensurate spin fluctuations were observed for ω⩾4meV, while no clear signal was observed at 2 meV, indicating an opening of spin gap. At ω=7meV, the peak-sharpening in momentum was observed in the superconducting state and the peak-intensity increases below Tc upon cooling. These results are quantitatively similar to those observed for the low-temperature-orthorhombic phase of optimarlly and slightly overdoped La2-xSrxCuO4 (LSCO), suggesting the reduction of hole concentration by Ce doping and no distinct effect from the lattice distortion on the spin fluctuations in the optimally doped LSCO.