ERC Advanced Grant Awarded to Physicist Tobias Kampfrath for His Research into Orbitronics at Terahertz Frequencies

Professor Tobias Kampfrath from Freie Universität Berlin will receive 2.5 million euros in funding from the European Research Council (ERC) for a period of five years to support his research project "ORBITERA." As part of this project, Kampfrath and a team of fellow experimental physicists will explore the fundamentals of novel concepts of magnetic data processing based on the orbital motion of electrons ("orbitronics"). To this end, they will develop new methods that rely on extremely short electromagnetic pulses in the terahertz frequency range. ERC Advanced Grants are awarded to well-established, prominent researchers who are looking to explore new fields of study.

Orbitronics is a relatively young field of research that aims to make information processing faster and more efficient. Modern technologies store and process information in the form of bits, where one bit corresponds to the information content "yes" or "no" or, equivalently, 1 or 0. In electronic devices such as laptops or smartphones, each of the billions of bits is encoded by the presence or absence of an electrical charge. Spintronics takes electronics one step further by enabling electronic devices to perform operations based not only on the charge of electrons, but also their spin. Electrons are constantly rotating around their own axes, and this spin generates a magnetic moment. The ability to make use of both an electron's charge and its spin simultaneously could be the key to creating faster and more powerful electronic devices. One important application of spintronics is as a type of nonvolatile memory, MRAM, which can be used as cache memory in central processing units. Orbitronics, on the other hand, is a very recent development in the field of electronics that focuses on the second type of rotation of which electrons are capable: orbital motion around an atom's nucleus. This form of technology aims to make use of orbital currents as information carriers and has the potential to make spintronic operations more efficient - and maybe even replace them.

"In ORBITERA, we want to find out how the orbital angular momentum of electrons can be transported through metals and how we can utilize it to speed up how magnetic information recorded," says Kampfrath. Because electrons collide with obstacles at such high speeds, the research group will be developing new methods to observe the flow of electrons and their orbits on the femtosecond time scale. To put this into perspective, within 100 femtoseconds, light - the fastest signal carrier - covers a distance equivalent to the width of a single human hair. In addition to gaining fundamental insights, Kampfrath expects the project to unearth new applications for orbitronics in the field of terahertz photonics. "For example, orbitronics could be used to generate ultrabroadband terahertz radiation, something that is becoming increasingly important for material characterization and quality control."

A professor of experimental physics at Freie Universität Berlin since 2017, Tobias Kampfrath studied physics in Erlangen and Göttingen (obtaining his diploma in 2001), and completed his doctoral studies at Freie Universität Berlin in 2006. Following a research stay at the Institute for Atomic and Molecular Physics (AMOLF) in Amsterdam (the Netherlands) as a postdoctoral researcher, he became principal investigator of the "Terahertz Physics" working group at the Fritz Haber Institute of the Max Planck Society in Berlin in 2010, where he established terahertz spintronics as a field of research. He has received the Carl Ramsauer Prize (2007), the Karl Scheel Prize (2014), and an ERC Consolidator Grant (2015) for his work. His current research interests lie in the behavior of spintronic nanostructures on the femtosecond time scale and at terahertz frequencies. He is cofounder of the start-up TeraSpinTec.