SPICE Workshop on Quantum Functionalities of Nanomagnets, June 17th - 19th 2025
Peter Fischer
Peter Fischer a,b
a Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA, USA
b Physics Department, University of California, Santa Cruz, CA, USA
Over several decades the paradigm in nanoscience was to interrogate materials properties behavior and their subsequent utilization in nanotechnologies by reducing the dimensions to obtain a deeper understanding of the fundamental building blocks in materials at the atomic and molecular level. Nanomagnetism has leveraged this concept in magnetic materials and spin systems. A plethora of new spin driven phenomena, such as the Giant Magnetoresistance (GMR) effect in thin films, has been discovered that built the foundation of spintronics. Interest in topological magnetic systems, such as skyrmions or Hopfions, have emerged over the last decade as they are not only scientifically fascinating objects, but hold the promise path to provide a solution towards low power, ultrafast and ultrasmall devices in future information and sensor technologies. So far, skyrmions have been treated mostly as classical objects, however, very recently there is strong interest to consider also quantum effects associated with skyrmion textures and the promise of exploiting them for quantum operations.
To explore the potential for using skyrmions in future quantum operations and systems, it is imperative to confirm their theoretically-predicted properties and behavior. Advanced validation techniques with spatial resolutions down to the atomic scale are necessary to image nanoscale skyrmions, while temporal resolutions down to the femtosecond regime will be required to facilitate studies of skyrmion dynamics in monophase materials as well as devices. Hybrid architectures will benefit from experimental approaches with high levels of layer and chemical sensitivities. Measurements of the quantum states of skyrmions will be accomplished via high-resolution spectroscopic techniques, such as nanoresolution Angle-Resolved Photoemission Spectroscopy (ARPES) or Scanning Tunneling Spectroscopy (STS). In-situ characterizations down to ultra-low temperatures and at variable magnetic fields will be critical to explore quantum-enabled functionalities, as will the capability to apply electrical currents in-operando. Experimental techniques that can address either global (macroscopic) spatially and temporally averaged quantities, e.g. total magnetization of an entire ensemble of quantum skyrmions, or local (microscopic) properties and behavior of individual quantum skyrmions with spatial resolution need to be employed.
I will review the current and future directions with various magnetic soft X-ray spectromicroscopies using polarized soft x-rays to provide unique characterization opportunities to study magnetic materials combining X-ray magnetic circular dichroism (X-MCD) as element specific, quantifiable magnetic contrast mechanism with spatial and temporal resolutions down to fundamental magnetic length, time, and energy scales.
Current developments and implementations of x-ray sources aim to increase dramatically the coherence of x-rays opening the path to new techniques, such as phase structured x-ray beams with large orbital angular momentum, ptychography with inherent magnetic phase sensitivity, or x-ray photo-correlation spectroscopy (XPCS) that allow unprecedented studies of nanoscale heterogeneity, complexity, and fluctuations.
This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division Contract No. DE-AC02-05-CH1123 in the Non-Equilibrium Magnetic Materials Program (MSMAG).
REFERENCE
- A Petrovic, Ch. Psadouraki, P. Fischer, M. Garst. Ch. Panagopoulos, arXiv:2410.11427