Exploring Coherent Manipulation of Spin Systems via the Near-Field of a Modulated Electron Beam

Abstract

Electron spin resonance (ESR) is a versatile analytical technique with broad applications in medicine, biology, and material science. While conventional ESR methods rely on magnetic field gradients or sophisticated resonator designs to provide spatial resolution, we explore an alternative approach utilizing the nonradiative near field of a modulated electron beam, implemented within a modified scanning electron microscope. Our custom-built in-situ ESR platform allows us to investigate the interaction between the modulated electron beam and solid-state spin systems. Using a benchmark sample (Koelsch radical, α,γ-bisdiphenylene-β-phenylallyl) and a conventional ESR detection scheme, we observe signatures compatible with spin interactions driven by the collective non-radiative near field of the beam. These findings establish a pathway toward coherent spin manipulation using a modulated, free-space electron beam, potentially enabling nanoscale spatial resolution for coherent quantum system control.