  The anomalous Hall effect (AHE), which in long-range ordered ferromagnets
appears as a voltage transverse to the current and usually is proportional to
the magnetization, often is believed to be of negligible size in
antiferromagnets due to their low uniform magnetization. However, recent
experiments and theory have demonstrated that certain antiferromagnets with a
non-collinear arrangement of magnetic moments exhibit a sizeable spontaneous
AHE at zero field due to a non-vanishing Berry curvature arising from the
quantum mechanical phase of the electron's wave functions. Here we show that
antiferromagnetic Mn5Si3 single crystals exibit a large AHE which is strongly
anisotropic and shows multiple transitions with sign changes at different
magnetic fields due to field-induced rearrangements of the magnetic structure
despite only tiny variations of the total magnetization. The presence of
multiple non-collinear magnetic phases offers the unique possiblity to explore
the details of the AHE and the sensitivity of the Hall effect on the details of
the magnetic texture.
