Hole-doping Dependence of Spin Excitation in Bi2201 High-Tc Cuprate

Abstract

We have succeeded in growing sizable single crystal of Bi_2+xSr_2-xCuO_6+y (Bi2201) High-T_c cuprates by improving frosting-zone method. Inelastic neutron scattering measurements on the single-layer cuprate Bi2201 with x=0.2, 0.3, 0.4 and 0.5 reveal existing of magnetic excitation signal at around (0.5, 0.5). The doping evolution of low energy magnetic excitation (ω ≦ 11 meV) was found as a change of incommensurate modulation wave vector from the [110] to [100]/[010] directions, and a linear relationship between the incommensurability and the hole concentration, δ~ p. On the other hands, the spectral weight is strongly suppressed with increasing hole concentration. Similarities and differences in the spin correlations between Bi2201 and the prototypical single-layer system La_2-xSr_xCuO₄ are discussed.