Classical and quantum dynamics of molecular spins on graphene

The classical and quantum dynamics of molecular spins on graphene.

Christian Cervetti, Angelo Rettori, Maria Gloria Pini, Andrea Cornia, Ana Repollés, Fernando Luis, Martin Dressel, Stephan Rauschenbach, Klaus Kern, Marko Burghard, Lapo Bogani

Nature Materials 15, 164 (2016)

a, |m_s sublevels of the ground state of the single-molecule-magnet [Fe₄(L)₂(dpm)₆], as obtained from equation (1). Absorption of phonons allows the barrier to be thermically overcome (green arrows). W ± n indicate the transition probabilities between magnetic |m states induced by the absorption (+) or emission (−) of n phonons. Quantum tunnelling happens between admixed levels (red arrows), whereas hyperfine and dipolar interactions create energy distributions (orange). Interaction with Dirac electrons increases the tunnel splittings below |3 and |−3 (red areas, exaggerated for clarity). b, Temperature and frequency dependence of the imaginary component of the dynamic susceptibility (χ′′) in a magnetic field H = 1 kOe for [Fe₄(L)₂(dpm)₆] (top) and hybrids with isolated molecules (bottom). Lines are simulations with the theory (see text for the theory). c, Temperature and frequency dependence of the real component of the dynamic susceptibility (χ′) in H = 0 for [Fe₄(L)₂(dpm)₆] (top) and hybrids with isolated molecules (bottom). Lines are simulations with the theory (see text for the theory).