Orbital Phenomena in Spintronic Systems

Orbital phenomena in spintronic systems extend the conventional focus on electron spin to include the orbital angular momentum of electrons as an information carrier. In orbitronics, orbital currents arise through mechanisms analogous to the spin Hall effect, enabling the transport of orbital angular momentum across nanometre to micrometre distances with reduced scattering. At interfaces and within multilayer stacks, the interplay of broken inversion symmetry, crystal field splitting and spin–orbit coupling gives rise to orbital Rashba–Edelstein effects, orbital torques and the efficient interconversion of orbital and spin currents. Such processes open routes to low‐power magnetization control, ultrafast terahertz emission and novel device paradigms that exploit long‐range ballistic propagation of orbital angular momentum. The combination of theoretical modelling and time‐resolved experiments has established orbital transport as a complementary channel to spin transport, with potential advantages in density, coherence length and materials versatility.

Research from Nature Portfolio

Recent studies have demonstrated direct time‐domain observation of ballistic orbital currents in magnetic thin films. Femtosecond optical excitation of Ni|W|SiO2 structures triggers orbital angular‐momentum pulses that propagate through tungsten over tens of nanometres with minimal decay, before conversion into charge currents by an inverse orbital Rashba–Edelstein process. Complementary terahertz emission experiments on Ni‐based multilayers show that light‐induced orbital currents dominate over concomitant spin currents and can be tracked via their characteristic time delays and propagation velocities. More recently, combined experimental and theoretical efforts have revealed giant orbital currents in ferromagnets and nonmagnets that travel over an order of magnitude further than spin currents. In these systems, orbital transport drives efficient magnetization switching with torque efficiencies surpassing those of purely spin‐based mechanisms, laying the groundwork for orbitronics‐based device applications.

Orbital Phenomena in Spintronic Systems publication trend

The graph below shows the total number of articles in orbital phenomena in spintronic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Orbitronics: The study and application of electron orbital angular momentum as an information carrier in solid‐state devices.

Orbital Hall effect: The generation of a transverse flow of orbital angular momentum in response to an applied electric field, analogous to the spin Hall effect.

Rashba–Edelstein effect (orbital): The induction of a non-equilibrium orbital polarization at a surface or interface with broken inversion symmetry under an applied electric field.

Spin–orbit torque: A torque exerted on magnetization arising from spin currents generated by spin–orbit coupling phenomena such as the spin Hall effect.

Orbital torque: A torque on a ferromagnet produced by the conversion of an injected orbital current into spin angular momentum via spin–orbit coupling.

References

1. Time-domain observation of ballistic orbital-angular-momentum currents with giant relaxation length in tungsten. Nature Nanotechnology (2023).
2. Orbitronics: light-induced orbital currents in Ni studied by terahertz emission experiments. Nature Communications (2024).
3. Observation of long-range orbital transport and giant orbital torque. Communications Physics (2023).
4. Orbital torque in magnetic bilayers. Nature Communications (2021).
5. Theory of current-induced angular momentum transfer dynamics in spin-orbit coupled systems. Physical Review Research (2020).
6. Giant orbital Hall effect and orbital-to-spin conversion in 3d, 5d, and 4f metallic heterostructures. Physical Review Research (2022).
7. Efficient conversion of orbital Hall current to spin current for spin-orbit torque switching. Communications Physics (2021).
8. Giant antidamping orbital torque originating from the orbital Rashba-Edelstein effect in ferromagnetic heterostructures. Nature Communications (2018).