Theory of Spin Resonance Spectroscopy in an Electron Microscope

Coherent spin resonance methods, such as nuclear magnetic resonance and electron spin resonance spectroscopy, have led to spectrally highly sensitive, non-invasive quantum imaging techniques. In this talk, I will present joint theoretical work with my collaborators* on a pump- probe spin resonance spectroscopy approach, designed for electron microscopy, based on microwave pump fields and electron probes [1]. Starting from the description of the coupling of free-electrons and localized sample spins, I will introduce the general method and discuss the size of the effect, in particular, the phase shift on the electron wave function and the corresponding deflection angle. I will also present a framework for the simulation of spin resonance spectroscopy in Transmission Electron Microscopy (TEM) that we have recently developed [2] and discuss our results on the quantum metrological precision limits associated with the technique and the optimal measurement strategy [3]. Notably, state-of-the-art TEM provides the means to detect signals almost as small as that due to a single electron spin in principle. This could enable state-selective observation of spin dynamics on the nanoscale.