Magnetic excitations in the stripe phase of high-T_c superconductors

The magnetic excitations in the stripe phase of high-T_c superconductors are investigated in a model of spin ladders which are effectively coupled via charged stripes. Starting from the effective single-triplon model for the isolated spin ladder, the quasi-one-dimensional spin system can be described straightforwardly. Very good agreement is obtained with recent neutron scattering data on La_(15/8)Ba_(1/8)CuO_4 (no spin gap) and YBa_2Cu_3O_(6.6) (gapped). The signature of quasi-one-dimensional spin physics in a single-domain stripe phase is predicted.