Magnetic Excitation in Lightly-Doped Bi_2.4Sr_1.6CuO_6+y

Abstract

We performed inelastic neutron scattering measurements in order to clarify the magnetic excitation of lightly-hole-doped Bi 2.4 Sr 1.6 CuO 6+y (Bi2201). At 7 K, a clear magnetic signal was observed up to 30 meV around (0.5, 0.5) reciprocal position, which corresponds to the antiferromagnetic zone center. The steeply extended excitation indicates the existence of high-energy spin excitation in the Bi2201 system, as was reported for La 2−x Sr x CuO 4 (LSCO). In the energy range between 10 meV and 30 meV, the intensity distribution in the momentum (h, k) plane is isotropic and the peak-width is wider than that in LSCO with the comparable hole-concentration. Furthermore, no well-defined inwardly dispersive excitation or the peak-sharpening with increasing the energy transfer was observed in the present Bi2201, unlike to the existence of hourglass-shaped excitation in LSCO.