Chiral Mesostructured NiO Films with Spin Polarisation

Spin polarisation is found in the centrosymmetric nonferromagnetic crystals, chiral mesostructured NiO films (CMNFs), fabricated through the symmetry‐breaking effect of a chiral molecule. Two levels of chirality were identified: primary nanoflakes with atomically twisted crystal lattices and secondary helical stacking of the nanoflakes. Spin polarisation of the CMNFs was confirmed by chirality‐dependent magnetic‐tip conducting atomic force microscopy (mc‐AFM) and magnetic field‐independent magnetic circular dichroism (MCD). Electron transfer in the symmetry‐breaking electric field was speculated to create chirality‐dependent effective magnetic fields. The asymmetric spin–orbit coupling (SOC) generated by effective magnetic fields selectively modifies the opposite spin motion in the antipodal CMNFs. Our findings provide fundamental insights for directional spin control in unprecedented functional inorganic materials. Chiral mesostructured NiO films are reported which exhibit chirality‐dependent spin polarisations of the moving electrons under either applied voltage or photoexcitation. An asymmetric effective magnetic field is induced with electron motion in the symmetry‐broken NiO. Thus, the antipodal chiral mesostructured NiO films exhibit asymmetric responses to the electron spin and result in opposite spin polarisations.