Shear stress (a) and viscosity (b) as a function of shear rate for sample 5Fe-15LVSA, under the application of magnetic fields of different strengths, H: solid line, H = 0 kA m−1; filled square, H = 73.5 kA m−1; filled diamond, H = 156 kA m−1; filled circle, 229 kA m−1; filled triangle, 282 kA m−1. (Online version in colour.)