Spintronic magnetic anisotropy

Abstract

An attractive feature of magnetic adatoms and molecules for nanoscale applications is their superparamagnetism, the preferred alignment of their spin along an easy axis preventing undesired spin reversal. The underlying magnetic anisotropy barrier --a quadrupolar energy splitting-- is internally generated by spin-orbit interaction and can nowadays be probed by electronic transport. Here we predict that in a much broader class of quantum-dot systems with spin larger than one-half, superparamagnetism may arise without spin-orbit interaction: by attaching ferromagnets a spintronic exchange field of quadrupolar nature is generated locally. It can be observed in conductance measurements and surprisingly leads to enhanced spin filtering even in a state with zero average spin. Analogously to the spintronic dipolar exchange field, responsible for a local spin torque, the effect is susceptible to electric control and increases with tunnel coupling as well as with spin polarization.

6 pages with 4 figures + 26 pages of Supplementary Information

References in corpus (8)

• Mechanical Control of Spin States in Spin-1 Molecules and the Underscreened Kondo Effect
• Kondo effect in quantum dots coupled to ferromagnetic leads
• Electric-field controlled spin reversal in a quantum dot with ferromagnetic contacts
• Electric Field Controlled Magnetic Anisotropy in a Single Molecule
• Density matrix numerical renormalization group for non-Abelian symmetries
• Properties of anisotropic magnetic impurities on surfaces
• Transport through quantum-dot spin valves containing magnetic impurities
• Magnetic-Field Dependence of Tunnel Couplings in Carbon Nanotube Quantum Dots