Route to Experimental Demonstrations of Altermagnetism by Prof Tomas Jungwirth

Join us at this seminar by Prof Tomas Jungwirth from the Czech Academy of Sciences. This seminar is organised as part of the IAS Frontiers Seminars: Quantum Horizons, jointly supported by the Institute of Advanced Studies (IAS) and School of Physical and Mathematical Sciences (SPMS).

About the seminar

The replacement of Flash memories by spintronic memories on advanced-node microprocessors has made ferromagnets vital complements of semiconductors in the present chip industry. The basic physical principle underpinning spintronic functionalities is time-reversal symmetry breaking. In ferromagnets, this takes the form of lifted Kramers degeneracy of the Fermi surface into majority- and minority-spin electronic states, giving rise to internal magnetisation. Since magnetisation limits scalability due to stray fields and hinders an energetically inexpensive transition from GHz to THz operation speeds, research has emerged towards spintronics without magnetisation. We first recall how this route was opened by realising that spin degeneracy does not necessarily exclude time-reversal symmetry breaking in the Fermi surfaces of some collinear antiferromagnets. Besides enabling spintronic memories with no stray fields and picosecond switching times, these antiferromagnets have entered quantum technologies by enabling a field-free and magnetisation-free superconducting diode. However, the absence of spin splitting remains a major roadblock, circumvented only through subtle and complex means of operating these devices. In the second part, we remove this roadblock by presenting experimental demonstrations of altermagnetism and spintronic devices based on this recently identified form of collinear magnetic order. Spin- and angle-resolved photoemission spectroscopy directly shows that the electronic band structure of altermagnets breaks time-reversal symmetry by spin-splitting electronic states despite vanishing magnetisation. This enables magnetisation-free altermagnetic devices to be operated by means analogous to ferromagnetic spintronics, as demonstrated in altermagnetic anomalous-Hall and spin-injection devices.

About the speaker

Tomas Jungwirth is a Head of the Department of Spintronics and Nanoelectronics at the Institute of Physics of the Czech Academy of Sciences, a Chair Professor at the University of Nottingham in the UK, and a Distinguished Professor at the Tohoku University in Japan. He is a recurrent Clarivate Highly Cited Researcher. He contribited to the discovery of the spin Hall effect, a phenomenon currently adopted by major semiconductor companies developing the next generation of magnetic random access memories. With collaborators, he initiated the field of antiferromagnetic spintronics by demonstrating proof-of-concept stray-field-free THz-speed spintronic memories. For the recent discovery of altermagnetism, Tomas Jungwirth was awarded, together with Libor Smejkal and Jairo Sinova, the 2026 Europhysics Prize by the European Physical Society.