MAGNETIC-STRUCTURES OF HCP BULK GADOLINIUM

We present results of self-consistent linear-muffin-tin-orbital calcul ations with the atomic-sphere approximation for hcp bulk Gd, using the local spin-density approximation (LSDA) and gradient correction (GC) for the description of exchange and correlation. In the LSDA calculati on antiferromagnetic order is favored over the ferromagnetic, and expe rimentally observed, structure. The GC weakens the bonding, leading to a higher equilibrium lattice parameter. At the new equilibrium volume the ground state is ferromagnetic. Our results point towards a magnet ic phase transition under pressure.