Bilayer-single-layer competition in artificial hybrid superlattices of square-lattice iridates

Controlling fundamental electronic and magnetic degrees of freedom via artificial heterostructure engineering is expected to provide a new way for obtaining new emergent quantum states. We successfully designed and synthesized a new hybrid superlattice (SL) of (SrIrO₃)₁/(SrTiO₃)₁/(SrIrO₃)₂/(SrTiO₃)₁ that combines single-layer and bilayer of Jeff = 1/2 square lattices which cannot be realized in the bulk materials. X-ray diffraction and resistivity measurements suggest that the hybrid SL hosts an intermediate electronic and structurally distorted state of the single-layer (SrIrO₃)₁/(SrTiO₃)₁ and bi-layer (SrIrO₃)₂/(SrTiO₃)₁ SLs. More interestingly, resonant x-ray magnetic scattering and magnetization measurements show that the hybrid SL stabilizes a unique magnetic state with a transition temperature similar to the bilayer SL but with a planar anisotropy similar to that of the single-layer SL. This may suggest that the hybrid state is closer to the quantum phase transition boundary between ab plane and c-axis magnetic states.