Spintronics has advanced memory and logic technologies by utilizing the electron's spin degree of freedom. In contrast, the electron's orbital angular momentum (OAM) was long regarded as quenched in transition metals due to crystal field effects and considered relevant only through spin–orbit coupling. Recent theoretical and experimental developments have overturned this view by revealing that Bloch states can host momentum-dependent orbital textures, enabling the generation and long-range transport of orbital currents even in light transition metals. This progress has given rise to the emerging field of orbitronics, which explores OAM as an active and tunable degree of freedom for information transfer and magnetization control. This review summarizes the fundamental mechanisms underlying orbitronics, including OAM generation via the orbital Hall effect and the orbital Rashba–Edelstein effect, the propagation and detection of orbital currents, and their conversion into efficient orbital torques on ferromagnets. We further highlight key experimental advances demonstrating long-range orbital transport and discuss how light-element materials can serve as effective orbital sources. Extending beyond electrons, we also examine the emergence of OAM in quasiparticles such as magnons and phonons, where twisted modes and valley pseudo-angular momentum reveal the universality of OAM physics. Together, these developments establish orbitronics as a new framework in condensed matter research, offering promising routes toward energy-efficient memory, logic, and sensing technologies.
Liao et al. (Thu,) studied this question.