Chapter 9
Magnetism of Individual Nanoparticles
Probed by X-Ray Photoemission Electron
Microscopy
Armin Kleibert
Abstract Magnetic nanoparticles are of great interest for applications in fields
ranging from biomedicine to spintronics. However, despite considerable work, their
size-dependent magnetic properties are still poorly understood. In this chapter, we
will introduce x-ray photoemission electron microscopy (XPEEM) as a spectromicroscopy technique ideally suited for the investigation of the magnetic properties of large numbers of individual nanoparticles in extended ensembles. Moreover,
XPEEM can be combined with other microscopy techniques to achieve a direct correlation between magnetism, size, shape, and structure of the very same nanoparticles.
This approach has led to the discovery of novel magnetic states in 3d transition
metal nanoparticles characterized by strongly enhanced magnetic energy barriers,
attributed to the strong impact of structural defects rather than to surface or interface
contributions to the total magnetic anisotropy.
9.1 Introduction
Magnetic nanoparticles are of interest for many applications in fields ranging from
spintronics to magnetic data storage, energy conversion, and biomedicine [1, 2].
This interest is due to the unique finite size effects that can occur in nanoparticles,
such as single domain states, superparamagnetism, enhanced magnetic moments or
magnetic anisotropy energies [3, 4]. Such properties hold great potential for novel
applications and are therefore extensively investigated. However, till today a quantitative understanding or control of size-dependent properties of magnetic nanoparticles has not been achieved. Instead, even for mono-disperse nanoparticle samples
of the canonical 3d transition metals, experiments yield widely scattering magnetic
anisotropy energies and magnetic moments [5]. This diversity is often explained by
shape, surface, structure or interface effects, but a quantitative interpretation of the
data is difficult, since most experiments concern integral measurements where the
A. Kleibert (B)
Paul Scherrer Institut, Swiss Light Source, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
e-mail: armin.kleibert@psi.ch
© Springer Nature Switzerland AG 2021
D. Peddis et al. (eds.), New Trends in Nanoparticle Magnetism,
Springer Series in Materials Science 308,
https://doi.org/10.1007/978-3-030-60473-8_9
219
Magnetism of Individual Nanoparticles
Probed by X-Ray Photoemission Electron
Microscopy
Armin Kleibert
Abstract Magnetic nanoparticles are of great interest for applications in fields
ranging from biomedicine to spintronics. However, despite considerable work, their
size-dependent magnetic properties are still poorly understood. In this chapter, we
will introduce x-ray photoemission electron microscopy (XPEEM) as a spectromicroscopy technique ideally suited for the investigation of the magnetic properties of large numbers of individual nanoparticles in extended ensembles. Moreover,
XPEEM can be combined with other microscopy techniques to achieve a direct correlation between magnetism, size, shape, and structure of the very same nanoparticles.
This approach has led to the discovery of novel magnetic states in 3d transition
metal nanoparticles characterized by strongly enhanced magnetic energy barriers,
attributed to the strong impact of structural defects rather than to surface or interface
contributions to the total magnetic anisotropy.
9.1 Introduction
Magnetic nanoparticles are of interest for many applications in fields ranging from
spintronics to magnetic data storage, energy conversion, and biomedicine [1, 2].
This interest is due to the unique finite size effects that can occur in nanoparticles,
such as single domain states, superparamagnetism, enhanced magnetic moments or
magnetic anisotropy energies [3, 4]. Such properties hold great potential for novel
applications and are therefore extensively investigated. However, till today a quantitative understanding or control of size-dependent properties of magnetic nanoparticles has not been achieved. Instead, even for mono-disperse nanoparticle samples
of the canonical 3d transition metals, experiments yield widely scattering magnetic
anisotropy energies and magnetic moments [5]. This diversity is often explained by
shape, surface, structure or interface effects, but a quantitative interpretation of the
data is difficult, since most experiments concern integral measurements where the
A. Kleibert (B)
Paul Scherrer Institut, Swiss Light Source, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
e-mail: armin.kleibert@psi.ch
© Springer Nature Switzerland AG 2021
D. Peddis et al. (eds.), New Trends in Nanoparticle Magnetism,
Springer Series in Materials Science 308,
https://doi.org/10.1007/978-3-030-60473-8_9
219