1301.6367 (L. Damewood et al.)

Bonding, magnetic properties and stability of the half-Heusler alloys
LiMnZ (Z=N, P, Si)    [PDF]

L. Damewood, B. Busemeyer, M. Shaughnessy, C. Y. Fong, L. H. Yang, C. Felser

We examined the bonding and magnetic properties, as well as the stability, of three magnetic half-Heusler alloys, namely LiMnZ, with Z=N, P or Si, in the three different atomic ordering of the C1_b crystal structure (i.e. alpha, beta, and gamma phases). At their respective optimized lattice constant, each material in the primitive cell is a ferromagnetic metal. Assuming a proper matching substrate could be found, alpha-LiMnN, LiMnSi in the beta and gamma phases, and LiMnP in the alpha and beta phases can be ferromagnetic half-metals at lattice constants larger than their optimized values. We also found that alpha-Li_{0.75}MnP, beta-Li_{0.75}MnZ, and pnictide gamma-Li_{0.75}MnZ can be half-metals at lattice constants slightly larger than the optimized values. Subsequently, we found that ferromagnetic LiMnZ obeys a modified Slater-Pauling curve, and all ferromagnetic Li_{0.75}MnZ, except for in the alpha phase, obey a similar curve. By comparing beta-LiMnP to the metastable zinc blende phase of MnP we determined the role of Li in the structure with respect to the elastic stability, electronic properties, and magnetic properties. Finally, we examined the possibility of antiferromagnetic ordering in these materials and found that by using the tetragonal unit cell, consisting of two formula units, LiMnN and LiMnP favor antiferromagnetic alignment.

View original: http://arxiv.org/abs/1301.6367