Rotation of magnetic propagation vectors induced by lattice clamping in (110)Eu films

Unique magnetic ordering has been observed in (110)Eu epitaxial films at low temperature: In contrast to bulk Eu, the magnetic helix propagating along the in-plane [001] direction vanishes on cooling below a temperature T-d, at the benefit of the other two. In addition, the two remaining propagation vectors continuously rotate towards the [110] growth direction. Both the temperature T-d and the rotation of wave vectors exhibit a pronounced dependence on film thickness, as a consequence of a thickness- and temperature-dependent lattice clamping effect that distorts the Eu lattice at low temperature.