"Vanadyl phthalocyanine: A computational study of a molecular scaffold for long-lived molecular spin states on surfaces"

Achieving quantum coherent control of spins on surfaces at the atomic scale is the goal for quantum coherent nanoscience. A good surface spin system requires two components: a localized spin and a buffer layer to isolate that spin from the metallic substrate. 

In this work, we used Vanadyl phthalocyanine (VOPc) as localized spin, a well-known spin = 1/2 molecule with long coherence times up to one microsecond in its crystalline form. The non-magnetic Titanyl phthalocyanine (TiOPc) is used as a buffer layer from the metal. We discuss the results of the electronic, structural, and magnetic properties of VOPc absorbed on TiOPc/Ag(100) by employing density functional theory, focusing on the role of TiOpc monolayer.

Different levels of complexity were employed for the approximation of the exchange-correlation functional (GGA, HSE) as well as Hubbard-U corrected GGA (GGA+U). Each component of the system was first individually characterized and compared with the experimental data.

We found that TiOPc is an effective buffer layer, preserving vacuum-like electronic structure of VOPc. We present compelling arguments for using TiOPc as self-assembling templates with long-range order for adsorbed VOPc molecules. In conclusion, this work shows that the TiOPc/VOPc system is a potential candidate for long-lived molecular spin states on surfaces.