Upper critical field of aD-wave superconductor stabilized by antiferromagnetic fluctuations

We have derived microscopic equations for the upper critical magnetic field of aD-wave superconductor stabilized by antiferromagnetic spin fluctuations. We present numerical results for the reduced fieldh _c2(t) as a function of reduced temperaturet when the magnetic field is along thez axis and also zero-order results when it is along thex ory axis. Two differentD-wave models are considered. The angular dependence ofH _c2 forT nearT _c is given as a function of polar angleϑ in thez−x orz−y plane.