Project B2: Engineering the Spin-Cascade in Radical-functionalized Lanthanide(III) bis- and tris-(phthalocyaninato) Complexes

DFG Research Areas: Condensed Matter Physics, Molecular Chemistry, Physical Chemistry

The aim of the project is to expand the field of spintronics of lanthanide(III) single molecule magnets (SMMs) within quantum devices by molecular design and to allow the read out of its quantum state. In particular, we focus on the engineering of the intrinsic spin-cascade, consisting of a ligand radical spin, the electronic spin and a hyper-fine coupled nuclear spin of the lanthanide metal ion, that enables to address the nuclear-spin based quantum register in quantum computing applications. Towards this goal, two series of radical-substituted Terbium (III) bis-phthalocyaninato and di-Terbium (III) tris-phthalocyaninato complexes, so-called double- and triple-decker molecules, will be synthesized. The double-decker molecules in their neutral forms display an intrinsic radical SZ = 1/2 delocalized over the two Pc ligands that has been used for indirect readout of the nuclear spin quantum system via the spin-cascade. The triple-deckers in their neutral form, however, lack this intrinsic radical. Thus, this project focuses on adding to both series of Terbium molecules additionally peripheric organic SExt = 1/2 substituents. This is of fundamental importance, since nuclear-spin manipulation via the exchange coupled electronic spin of the lanthanide ion, which is itself hyperfine coupled to its nuclear spin, requires the access to unpaired organic radicals on the ligand as a handle. Furthermore, when the radical is attached to the central Pc ligand of the triple-decker, it can also mediate an indirect exchange between the two lanthanide(III) ions to create the product states that span the larger Hilbert space. The objective is to synthesize radical-decorated double- and triple-decker complexes with the goal to investigate the impact of additional exchange interaction via an external radical spin on the spin-cascade. 

Project leaders: 
Prof. Dr. Wulf Wulfhekel (KIT) 
Prof. Dr. Mario Ruben (KIT)