Congratulations to Antonin Jaroš on receiving the Fritz-Grasenick-Award for his work on “Sensing Spin Precession with Free Electrons.” His research highlights exciting progress in sensing spin dynamics with free electrons at the interface of electron microscopy, magnetic resonance, and quantum physics. The award-winning research were carried out in the group of Assoc. Prof. Philipp Haslinger at USTEM, TU Wien. The work is published in the ACS Nano article “Sensing Spin Precession with Free Electrons”.

Sensing Spin Precession with Free Electrons
Antonín Jaroš, Michael S Seifner, Johann Toyfl, Benjamin Czasch, Santiago Beltrán-Romero, Isobel C Bicket, Philipp Haslinger
ACS Nano, 20, 4, 3435 (2026)

The work is on a novel method that combines spin resonance spectroscopy with transmission electron microscopy (TEM), enabling localized in-situ detection of microwave (MW)-driven spin excitations. Our approach utilizes continuous wave MW excitation at GHz frequencies, while employing the free-space electron beam as a signal receiver to sense spin precession. Spin state polarization is achieved via the magnetic field of the TEM’s polepiece, while a custom-designed microresonator integrated into a TEM sample holder drives spin transitions and modulates the electron beam. This modulation enables phase-locked detection with picosecond temporal resolution, allowing the isolation of spin precession contributions to the electron beam deflection with a sensitivity of  ~280 prad. The presented technique lays foundations for the MW spectroscopic in-situ exploration of spin dynamics at the nanoscale.