Size of linear superpositions in molecular nanomagnets

Molecular nanomagnets are zero-dimensional spin systems that exhibit quantum-mechanical behavior at low temperatures. Exploiting quantum-information theoretic measures, we quantify here the size of linear superpositions that can be generated within the ground multiplet of high-and low-spin nanomagnets. Amongst the former class of systems, we mainly focus on Mn-12 and Fe-8. General criteria for maximizing such measures are also outlined, and illustrated with reference to spin clusters of different geometries. The actual character (micro or macroscopic) of linear superpositions in low-spin systems is inherently ill-defined. Here, this issue is addressed with specific reference to the Cr7Ni and V-15 molecules, characterized by an S = 1/2 ground state. In both cases, the measures we obtain are larger than those of a single s = 1/2 spin but not proportionate to the number and value of the constituent spins.