Vanadyl Phthalocyanine single molecules on insulating layers; ultrathin MgO film and Titanyl Phthalocyanine monolayer

Molecular spin is drawing attention as quantum processing platform due to its chemical tunability and scalability. Vanadyl Phthalocyanine (VOPc) is one of the promising molecular qubit candidates, yet it shows signs of strong coupling with scattering electrons when directly sitting on metal surface. Herein, we investigate VOPc single molecules on different insulating layers, magnesium oxide (MgO) bilayer and Titanyl Phthalocyanine (TiOPc) monolayer. By combined study of scanning tunneling spectroscopy (STS) and X-ray circular dichroism (XMCD), we confirm that VOPc in both systems are well decoupled from the metallic substrate, while retaining the pristine molecular spin characteristics. Furthermore, we discuss the novel properties of VOPc - symmetry reduction when adsorbed on MgO film and formation of long-range ordering on molecular template - in combination with density function theory (DFT) calculations. Our work provides a viable method towards the future integration of molecular spin qubits into solid-state quantum devices.