  We use a concerted theory-experiment effort to investigate the formation of
chiral real space spin texture when the archetypal Dirac semimetal Cd$_3$As$_2$
is interfaced with In$_{1-x}$Mn$_x$As, a ferromagnetic semiconductor with
perpendicular magnetic anisotropy. Our calculations reveal a nonzero
off-diagonal spin susceptibility in the Cd$_3$As$_2$ layer due to the Rashba
spin-orbit coupling from broken inversion symmetry. This implies the presence
of a Dzyaloshinskii-Moriya interaction between local moments in the
In$_{1-x}$Mn$_x$As layer, mediated by Dirac electrons in the vicinal
Cd$_3$As$_2$ layer, potentially creating the conditions for a real space chiral
spin texture. Using electrical magnetoresistance measurements at low
temperature, we observe an emergent excess contribution to the transverse
magneto-resistance whose behavior is consistent with a topological Hall effect
arising from the formation of an interfacial chiral spin texture. This excess
Hall voltage varies with gate voltage, indicating a promising
electrostatically-tunable platform for understanding the interplay between the
helical momentum space states of a Dirac semimetal and chiral real space spin
textures in a ferromagnet.
