Epitaxial Bain path of antiferromagnetic tetragonal Mn

The epitaxial Bain path (EBP) of antiferromagnetic (AF) tetragonal Mn has b een found by first-principles total-energy calculations using the full-pote ntial linearized-augmented-plane-wave (FLAPW) method with two different pot entials: (1) the local-spin-density-approximation without relativistic corr ections (LSDA-NREL) and (2) the Perdew-Burke-Ernzerhof exchange-correlation potential in a generalized-gradient-approximation with relativistic correc tions (GGA-REL). The EBP from the GGA-REL calculations shows that the tetra gonal ground state of AF Mn is at c/a=0.949, in close agreement with the ex perimental value for gamma-Mn at c/a =0.946, but the LSDA-NREL value 0.993 is not as close. The LSDA-NREL calculations show that when grown epitaxiall y on Pd(001), the AF Mn film is strained gamma-Mn, but grown on V(001) the film is strained delta-Mn. The GGA-REL calculation also finds the Mn film o n Pd(001) is strained gamma-Mn, but on V(001) is unstable. Lattice constant s for both the ground state and the metastable equilibrium state and tetrag onal elastic constants for the ground state are determined with both potent ials.