ELECTRONIC-STRUCTURE AND MAGNETOVOLUME INSTABILITIES OF THE HEXAGONALLAVES PHASE COMPOUND FE2TI

We investigate the electronic and cohesive properties of the hexagonal and cubic Laves phases of Fe2Ti by ab initio band structure calculati ons. In particular the stability range of these compounds is studied. In the volume range considered, the state of lowest energy is hexagona l (C14) and exhibits antiferromagnetic order. However, we find a sligh tly higher in energy lying ferromagnetic state with low magnetic momen t (smaller than 1 mu(B)). Interestingly enough, this moment can consid erably be enhanced (larger than 1.5 mu(B)) for larger lattice spacings . The characteristic moment-volume dependence of the Fe atom can also account for the experimental observation that Fe2+xTi1-x is ferromagne tic for x > 0 since the smaller Fe atom leads to a contraction of the lattice which stabilizes large ferromagnetic iron clusters.