Magnetic phase competing in MnAu systems

First-principles total energy calculations on tetragonal MnAu superlattices are performed by means of the self-consistent full-potential linearized augmented-plane-wave method under the generalized gradient approximation. It is shown that the stability of the spin configuration strongly depends on the lattice distortion due to its competitive nature. Using Monte Carlo simulations with exchange parameters deduced from ab initio results, finite-temperature magnetism is also studied and a magnetic phase diagram connected with lattice distortion is obtained.