Abstract
We measured the inelastic neutron scattering of slightly overdoped high-Tc superconductor Bi2.1Sr1.9CaCu2O8+δ (Bi2212: Tc=86.2±3.5 K). We observed the enhancement of a commensurate peak at (1⁄2,1⁄2,−14) and ω∼34 meV in the superconducting state, which is similar to the previously reported resonance peak in the YBa2Cu3O6+x (YBCO) and Bi2212 systems. However, the temperature dependence above Tc is different: substantial resonance spectral weight remains above Tc, and shows a sharp drop at T∼200 K, which roughly agrees with the onset of the pseudogap (T*). We propose that the different thermal variations of the magnetic excitations in high-Tc superconductors can be understood in terms of the pseudogap phase and redistribution of the magnetic spectral weight across Tc and T*.
