Superconductivity without diamagnetism in systems with broken time-reversal symmetry

We analyze the phase diagram of superconductors with a broken time-reversal symmetry in an external magnetic field. Ferromagnetism (broken time-reversal symmetry) originates either from the electron spin or the intrinsic angular momentum of Cooper pairs (chiral p -wave superconductors such as Sr2 RuO4). In addition to the Meissner and the mixed states, the phase diagram includes also the cryptoferromagnetic state with intrinsic domain structure independent of sample shape and size. The cryptoferromagnetic state is not diamagnetic and can be detected by observation of magnetization curves predicted in the present analysis.