We investigate the influence of ferromagnet crystalline structures on spin Hall angle (SHA) in ferromagnet (FM)/heavy metal (HM) bilayers with reversed stacking order. X-ray diffraction and transmission electron microscopy show that a pronounced permalloy (Py) (111) texture emerges in substrate/Ta/Py compared to that in substrate/Py/Ta. Spin torque ferromagnetic resonance measurements show that the out-of-plane SHA (θ⊥, associated with Rashba-like effective field) is ∼2 times larger in substrate/Ta/Py than that in substrate/Py/Ta, while in-plane SHA (θǁ, associated with spin Hall-like effective field) shows no distinct difference. We ascribe the FM structure dependent SHA to the interfacial symmetry breaking between the FM and HM, which is tuned by the work functions due to different crystalline structures of the FM. The emergence of the Py (111) structure enlarges the interfacial symmetry breaking and consequently enhances the Rashba effect at the FM/HM interface.
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