Observation of nanoscale magnetic fields using twisted electron beams

Abstract

Electron waves give an unprecedented enhancement to the field of microscopy by providing higher resolving power compared to their optical counterpart. Further information about a specimen, such as electric and magnetic features, can be revealed in electron microscopy because electrons possess both a magnetic moment and charge. In-plane magnetic structures in materials can be studied experimentally using the effect of the Lorentz force. On the other hand, full mapping of the magnetic field has hitherto remained challenging. Here we measure a nanoscale out-of-plane magnetic field by interfering a highly twisted electron vortex beam with a reference wave. We implement a recently developed holographic technique to manipulate the electron wavefunction, which gives free electrons an additional unbounded quantized magnetic moment along their propagation direction. Our finding demonstrates that full reconstruction of all three components of nanoscale magnetic fields is possible without tilting the specimen.

Magnetic characterization of cobalt nanowires and square nanorings fabricated by focused electron beam induced deposition

“…Following this argument, the B value measured in our nanowires should be 15% higher than that for vertical nanopillars with the same Co purity. This turns out to be in perfect agreement with our recent work [ 39 ], where a B value of 1.1 T was measured for vertical Co nanopillars having the same composition, within experimental error, as the nanowires presented here. Taken together, these results indicate that on-substrate deposition at lower energy is more suitable for obtaining highly magnetic NWs.…”

Generation and detection of spin-orbit coupled neutron beams

“…Photonic OAM has demonstrated usefulness in edge-detection microscopy, quantum information processing protocols, encoding and multiplexing of communications, and optical manipulation of matter (8–15). Electron OAM beams have found applications in the characterization of nanoscale magnetic fields in materials (16) and exploration of magnetic monopoles (17). Neutron OAM has shown promise in the detection of buried interfaces (18).…”

Coiling free electron matter waves

“…Current work utilizing off-axis holograms within a TEM allows for a high degree of control over the structure of a diffracted electron beam [9][10][11][12]. Electron vortex beams have applications in numerous scientific studies, including potential magnetic monopole detection [13][14][15], measuring magnetic properties [16][17][18], atomic scale resolution techniques [19], and magnetic dichroism experiments [20]. In all these works, it should be noted that the term 'vortex' here denotes the phase of the wavefunction only; not the motion.…”