  The conventional Hall effect is linearly proportional to the field component
or magnetization component perpendicular to a film. Despite the increasing
theoretical proposals on the Hall effect to the in-plane field or magnetization
in various special systems induced by the Berry curvature, such an
unconventional Hall effect has only been experimentally reported in Weyl
semimetals and in a heterodimensional superlattice. Here, we report an
unambiguous experimental observation of the antisymmetric planar Hall effect
(APHE) with respect to the in-plane magnetic field in centrosymmetric rutile
RuO2 and IrO2 single-crystal films. The measured Hall resistivity is found to
be linearly proportional to the component of the applied in-plane magnetic
field along a particular crystal axis and to be independent of the current
direction or temperature. Both the experimental observations and theoretical
calculations confirm that the APHE in rutile oxide films is induced by the
Lorentz force. Our findings can be generalized to ferromagnetic materials for
the discovery of anomalous Hall effects and quantum anomalous Hall effects
induced by in-plane magnetization. In addition to significantly expanding
knowledge of the Hall effect, this work opens the door to explore new members
in the Hall effect family.
