X-ray magneto-optics of lanthanide materials: principles and applications

Abstract

Lanthanide metals are a particular class of magnetic materials in which the magnetic moments are carried mainly by the localized electrons of the 4f shell. They are frequently found in technically relevant systems, to achieve, e.g., high magnetic anisotropy. Magnetooptical methods in the x-ray range are well suited to study complex magnetic materials in an element-specific way. In this work, we report on recent progress on the quantitative determination of magneto-optical constants of several lanthanides in the soft x-ray region and we show some examples of applications of magneto-optics to hard-magnetic interfaces and exchange-coupled layered structures containing lanthanide elements.

Magnetism of orderedSm∕Co(0001)surface structures

“…The photon-energy range extending to some 10 eV below the resonance max- ima is particulary sensitive to interference, favoured by the long x-ray penetration length due to reduced absorption (small imaginary part of the refractive index n) and to the absence of total internal reflection (real part of n larger than 1). 16,17 The spectra of both structures contain magnetic contrast, allowing to perform XMOKE measurements at the Sm M 5 and Co L 3 thresholds. XMOKE curves for the Sm(1 ML)/Co/W(110) phase recorded at an incidence angle of 10 • are shown in the insert of Fig.…”

Temperature-Induced Reversal of Magnetic Interlayer Exchange Coupling

“…In these trilayers, the exchange coupling between the two magnetic layers acts as an effective bias field (exchange bias) that needs to be overcome in order to reverse the magnetization of the softer layer. The resulting shift of the Gd hysteresis curve with respect to zero field is a measure of the coupling strength [21]. As an example, Fig.…”