Effect of uniaxial pressure on helimagnetic structure in Lu2Fe17

The incommensurate helimagnetic structure (IHS) in the Lu2Fe17 intermetallics has been induced at 5 K by hydrostatic pressure above 0.3 GPa and characterized by a propagation vector (00tz). The observed dependence of tz on external variables is discussed within a simple model based on a complex dependence of exchange interactions Jn,m (n, m = f, j, k and g) on distances between Fe-atoms in inequivalent positions 4f, 12j, 12k and 6g of the hexagonal P63/mmc crystal structure. To verify this model, we have studied magnetization and representative neutron reflections of Lu2Fe17 single crystals under high hydrostatic pressure and uniaxial compression with stress σ || a-axis and σ || c-axis. Both, the metamagnetic transitions and magnetic satellites of the (00tz) type that verify the presence of IHS in Lu2Fe17 at 5 K were observed under hydrostatic pressure and under uniaxial stress σ || c-axis only. We show that the dominant role in an appearance of IHS in the Lu2Fe17 under compression is played by the Jff and Jfj exchange interactions.