Magnetic excitations of the diagonal incommensurate phase in lightly-doped LaSrCuO

Matsuda, Masaaki; Fujita, Masaki*; Wakimoto, Shuichi  ; Fernandez-Baca, J. A.*; Tranquada, J. M.*; Yamada, Kazuyoshi*

Neutron scattering experiments were performed in lightly-doped LaSrCuO to study the magnetic excitations in the insulating phase with the diagonal incommensurate spin correlations. It was found that the magnetic excitations at low temperatures are similar to those in the superconducting phase with parallel incommensurate spin correlations. The overall excitation has an hour-glass shape with 15-25 meV. ( is an energy at which the low-energy excitations cross the antiferromagnetic wave vector.) Furthermore, the effective velocity of the low-energy excitations is approximately independent of doping, so that scales linearly with doping, following the elastic limit of the magnetic incommensurability. This supports the concept that the magnetic excitations evolve directly from the antiferromagnetic insulator.