Detailed study of the structure of the low-energy magnetic excitations in overdoped La1.75Sr0.25CuO4

Abstract

To examine the detailed structure of low-energy magnetic excitations in a high-transition-temperature superconducting cuprate with heavily hole-doping, we performed inelastic neutron scattering experiments on La1.75Sr0.25CuO4. We observed clear dispersion relations of the previously reported incommensurate (IC) magnetic correlations at Qtet=(0.5±δ,0.5)/(0.5,0.5±δ)[1]. In addition, we show the emergence of continuum magnetic excitations with a ring shape centered at Γ point Qtet=(0.5,0.5) in a constant energy spectrum at T=50K. The radius of the ring (r=0.109) is smaller than the incommensurability (δ=0.118). This suggests that the origin of the ring-like excitations is different from that of the IC magnetic correlations, and the low-energy magnetic excitations of the La2-xSrxCuO4 system are inherently composed of these two kinds of excitations.