Challenges and opportunities in orbitronics

The spin of the electron has been a key enabler to realize spintronics devices that harness the spin degree of freedom beyond conventional charge-based electronics. In addition to spin, electrons have another degree of freedom associated with the angular momentum: orbital angular momentum. While spintronics has evolved fast and spintronics concepts are now used in magnetic sensors and nonvolatile memories, exploiting orbital angular momentum has just started to be studied. Phenomena mediated by orbital angular momentum have led to a new branch of spintronics called orbitronics. This Perspective discusses how orbitronics can constitute the next step in the evolution of spintronics by reviewing the current understandings and experimental results of orbital effects and summarizing the open questions. Prospects and challenges for devices in particular in non-volatile memory are discussed as an applications perspective.