Noninvasive Electrical Detection of Electron Spin Dynamics at the N Atom in N@C60

Abstract

Endohedral N@C₆₀ contains an electron spin of S = 3/2 at the central N atom, which, shielded by the C₆₀ cage, has an extremely long spin relaxation time. The π-conjugated C₆₀ cage, when connected to electrodes, provides a highly conductive path for electron transport and enables a noninvasive electrical detection of dynamics of the central spin. Here we use the Keldysh non-equilibrium Green’s function and establish a microscopic description of how spin dynamics, including resonance and relaxation, can manifest itself in the device conductance. We predict that magnetic electrodes can enhance the detectivity by orders of magnitude compared with nonmagnetic electrodes. It is shown that this electrical detection is more sensitive to the longitudinal spin component than the transverse one. Hence the transient spin nutation is particularly useful in determining spin decoherence time T₂ in such transport device structures. This theory can be used to describe recent experiments of electrically detected spin dynamics in C₆₀ and other systems.