  It has recently been shown that in a broad class of disordered systems
oscillatory shear training can embed memories of specific shear protocols in
relevant physical parameters such as the yield strain. These shear protocols
can be used to change the physical properties of the system and memories of the
protocol can later be "read" out. Here we investigate shear training memories
in colloidal gels, which include an attractive interaction and network
structure, and discover that such systems can support memories both along and
orthogonal to the training flow direction. We use oscillatory shear protocols
to set and read out the yield strain memories and confocal microscopy to
analyze the rearranging gel structure throughout the shear training. We find
that the gel bonds remain largely isotropic in the shear-vorticity plane
throughout the training suggesting that structures formed to support shear
along the training shear plane are also able to support shear along the
orthogonal plane. Orthogonal memory extends the usefulness of shear memories to
more applications and should apply to many other disordered systems as well.
