Magnetic materials have become controllable on the nanometre scale. Such fine structures exhibit a wide range of fascinating phenomena, such as lowdimensional magnetism, induced magnetization in noble metals, electron interference patterns, oscillatory magnetic coupling and 'giant' magnetoresistance. Magnetic multilayers with nanometre spacings are among the first metallic quantum structures to become incorporated into electronic devices, such as reading heads for hard discs. This article is intended to familiarize the reader with the physics and technology of magnetic nanostructures. It starts out with recent progress in nanofabrication, gives a tutorial on the connection between electronic states and magnetic properties, surveys the state of the art in characterization techniques, explains unique phenomena in two-, one- and zero-dimensional structures, points out applications in magnetic storage technology and considers fundamental limits to storage density. Particular emphasis is placed on the connection between magnetism and the underlying electronic states, such as the spin-split energy bands, s, p versus d states, surface states, and quantum well states.

Using inverse photoemission and photoemission we find that the bulk bands become discretized in highly perfect layer structures, such as Cu on fcc Co(100), Cu on fcc Fe(100), Ag on bcc Fe(100), Au on bcc Fe (100), fcc Co on Cu(100), and bcc Fe on Au(100). The electronic structure is analyzed in the framework of quantum-well states consisting of bulk Bloch functions modulated by an envelope function. The wavelength of the envelope function is determined from the λ/2 interferometer fringes produced by the periodic appearance of quantum-well states with increasing film thickness. Using k conservation, one obtains an absolute measurement of the band dispersion for the s,p bands of Fe, Cu, Ag, and Au. Quantum-well states at the Fermi level are found to be closely connected with oscillatory magnetic coupling in superlattices. They are spin polarized, even in noble metals, due to the spin-dependent band structure of the confining ferromagnet. The oscillation period is half the wavelength of the envelope function. The corresponding wave vector is given by the Fermi wave vector and by the wave vector of the nearest s,p band edge via 2(${\mathit{k}}_{\mathrm{edge}}$-${\mathit{k}}_{\mathit{F}}$). This turns out to be equivalent to Ruderman-Kittel-Kasuya-Yosida theory.

Quantum well states are found at the Fermi level in Cu on Co(100) and Ag on Fe(100) using inverse photoemission. They appear every 5.9±0.5 layers in Cu/Co(100), which agrees with the 5.5- to 6-layer oscillation period of the magnetic coupling in Cu/Co(100) superlattices. For Ag/Fe(100) they connect with minority-spin interface states observed below ${\mathit{E}}_{\mathit{F}}$ previously, providing a magnetic coupling channel through the noble metal. These properties are explained in terms of the bulk band structure.

Contributing to the need for new graphene nanoribbon (GNR) structures that can be synthesized with atomic precision, we have designed a reactant that renders chiral (3,1)-GNRs after a multistep reaction including Ullmann coupling and cyclodehydrogenation. The nanoribbon synthesis has been successfully proven on different coinage metals, and the formation process, together with the fingerprints associated with each reaction step, has been studied by combining scanning tunneling microscopy, core-level spectroscopy, and density functional calculations. In addition to the GNR’s chiral edge structure, the substantial GNR lengths achieved and the low processing temperature required to complete the reaction grant this reactant extremely interesting properties for potential applications.

We present Auger-electron spectroscopy, low-energy electron diffraction, and $\Delta \phi$ measurements of Cs adsorption on Si(100) and subsequent oxidation of the substrate. Our data provide evidence against complete charge transfer from the alkali metal to Si as proposed recently. The amount of Si${\mathrm{O}}_2$ produced by alkali-metal-promoted low-temperature oxidation of silicon is found to be strictly proportional to the alkali-metal coverage, which, together with measured changes in the work function during oxidation, allows us to question some of the current mechanisms put forward to explain this phenomenom.