X-Ray Imaging of Magnetic Structures

Abstract

The characterization of nanoscale magnetic structures, their static properties, and fast spin dynamics with polarized soft X-rays has become an indispensable analytical tool due to the unique features of those probes. The spectroscopic magnetic response serves as a fingerprint of the specimen and can give quantitative information on element-specific spin and orbital magnetic moments. Images of magnetic domain structures at a spatial resolution down to nearly 10 nm, ultimately in all three dimensions, can be obtained with various X-ray microscopy techniques and can further be combined with stroboscopic pump-probe schemes to image the spin dynamics of spin structures, such as the motion of domain walls in nanowires or the vortex core dynamics in micropatterned magnetic elements. Next generation sources of polarized soft X-rays such as X-ray free electron lasers or high-harmonic generation laser sources hold the promise to provide nanometer spatial and femtosecond time resolution, enabling to address thus fundamental magnetic length and time scales in magnetism. This paper reviews the various X-ray imaging techniques using polarized soft X-rays by summarizing their characteristic features, recent achievements, and current limitations as well as future opportunities. A brief overview on other magnetic imaging techniques are given to set magnetic X-ray imaging techniques into context. Index Terms-Magnetic diffractive imaging, photoemission electron microscopy, soft X-ray spectromicroscopy, spin dynamics, X-ray magnetic circular dichroism (XMCD), X-ray optics. 0018-9464

Magnetic coupling of vortices in a two-dimensional lattice

“…For temperature dependent measurements additionally a liquid nitrogen cryogenic sample stage was used, which allows measurements in the temperature range between 77 and 500 K. Furthermore, direct observation of vortex structures was carried out using fullfield magnetic transmission soft x-ray microscopy (MTXM) at the Advanced Light Source (beamline 6.1.2.) in Berkeley (CA, USA), enabling real-space magnetic imaging with highspatial resolution down to 20 nm [46]. In MTXM, magnetic contrast is given by x-ray magnetic circular dichroism, arising from the dependence of the x-ray absorption coefficients on the orientation between magnetization and photon helicity [46].…”

Coherent Resonant Soft X-ray Scattering Study of Magnetic Textures in FeGe

“…The method is extremely useful for the structural examination of non-crystalline specimens [1][2][3][4], and can be applied for the determination of the exact positions of individual scattering objects and the mapping of defects in periodically ordered structures [5,6]. One of the promising applications of coherent soft X-rays is the imaging of the local magnetization of magnetic specimens [7]. In the soft X-ray regime, by exciting electrons from the 2p state to the 3d state of transition-metal atoms, it is possible to study the magnetic ordering in wide-angle diffraction [8][9][10] or small-angle scattering geometry [11][12][13][14][15].…”

Broadband Generation of Orbital Angular Momentum Carrying Beams in Rf Regimes

“…In recent years, electromagnetic fields carrying orbital angular momentum (OAM) have captured attention due to their fascinating properties and broad application prospects in various fields such as quantum entanglement [1], electron vortex [2,3], microscopy and imaging [4,5], neutron control [6], remote sensing [7], and optical tweezers [8]. Especially in information science [9][10][11][12], the mutually orthogonal feature of OAM modes may increase spectral efficiency and system capacity.…”