Incommensurate Magnetic Excitation in Spin-Glass Phase of Bi2201 Cuprate

Static and dynamic magnetic susceptibilities of lightly-doped Bi 2.4 Sr 1.6 CuO 6+ y were studied by a SQUID magnetometer and triple-axis neutron spectrometers. The static magnetic susceptibility showed a difference between field-cooled and zero-field-cooled processes at low temperature, showing a spin-glass-like behavior. The irreversibility temperature was determined to be T sg ∼3 K, which is slightly lower than T sg of 5–6 K in the lightly-doped LSCO with similar hole concentration. Furthermore, we have confirmed the existence of low-energy spin fluctuations with the spatially modulated spin correlation along diagonal to Cu–O bond direction in the Bi2201 system for the first time. This observation is consistent with the previously reported result for the spin-glass phase of LSCO. The magnetic intensity χ ′′ (ω) measured at the energy transfer of 1 meV drastically developed below 100 K, while that at 6 meV shows a gradual increase below 200 K with decreasing the temperature. Although the spin fluctuatio...