  Electrical manipulation of spin textures inside antiferromagnets represents a
new opportunity for developing spintronics with superior speed and high device
density. Injecting spin currents into antiferromagnets and realizing efficient
spin-orbit-torque-induced switching is however still challenging due to the
complicated interactions from different sublattices. Meanwhile, because of the
diminishing magnetic susceptibility, the nature and the magnitude of
current-induced magnetic dynamics remain poorly characterized in
antiferromagnets, whereas spurious effects further complicate experimental
interpretations. In this work, by growing a thin film antiferromagnetic
insulator, {\alpha}-Fe2O3, along its non-basal plane orientation, we realize a
configuration where an injected spin current can robustly rotate the N\'eel
vector within the tilted easy plane, with an efficiency comparable to that of
classical ferromagnets. The spin-orbit torque effect stands out among other
competing mechanisms and leads to clear switching dynamics. Thanks to this new
mechanism, in contrast to the usually employed orthogonal switching geometry,
we achieve bipolar antiferromagnetic switching by applying positive and
negative currents along the same channel, a geometry that is more practical for
device applications. By enabling efficient spin-orbit torque control on the
antiferromagnetic ordering, the tilted easy plane geometry introduces a new
platform for quantitatively understanding switching and oscillation dynamics in
antiferromagnets.
