Figure 1

(a) Magnetic cycloid wave vectors ${\tau }_i$, the (111) direction normal to these vectors, and the direction of the applied pressure $P$ in the pseudocubic unit cell of ${\mathrm{BiFeO}}_3$. The spins are confined in the 3 “easy” planes defined by the (111) and the ${\tau }_i$ vectors. Two of these planes are shaded, and the dotted arrow shows the pressure-induced rotation of the spins from one of these planes to another. Panel (b) illustrates lifting of the magnetic domain degeneracy by pressure, as explained in the text.Reuse & Permissions

Figure 2

Magnetic scattering in the vicinity of $Q_0=(0.5,0.5,0.5)$ in the plane defined by (111) and ${\tau }_1$. (a) The initial scattering pattern at $P=0$. (b) The initial zero-pressure scan through $Q_0$ along the ${\tau }_1$ direction. The solid line is the fit described in the text, the dashed lines show the corresponding in- and out-of-plane domain contributions. (c) Scans taken at different uniaxial pressures. (d) The scan at $P=7.2\mathrm{MPa}$ and the fits with zero (dashed line) and nonzero (solid line) in-plane domain contributions, as discussed in the text. (e) The scattering pattern at $P=7.2\mathrm{MPa}$. The tilted shape of the peak is due to instrumental resolution effects. In all panels, error bars (1 standard deviation) are from counting statistics.Reuse & Permissions

Figure 3

Scans through the $Q_0$ position along ${\tau }_1$ (a), and along ${\tau }_3$ (b) directions taken at $P=0$ after the pressure was applied and then removed. The insets show the overall scattering patterns in the corresponding scattering planes. Solid lines are fits described in the text. Dashed lines in (b) show the calculated in- and out-of-plane domain contributions to scattering. Error bars (1 standard deviation) are from counting statistics.Reuse & Permissions