6533b7dbfe1ef96bd126fe77

RESEARCH PRODUCT

Threshold photoemission magnetic circular dichroism at the spin-reorientation transition of ultrathin epitaxial Pt/Co/Pt(111)/W(110) films

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X-ray magnetic circular dichroism (MCD) is nowadays widely used for the investigation of magnetic properties of surfaces and thin films. Recently, similarly large effects have been observed for UV-VIS MCD effects both in single [1] and two-photon photoemission [2-3]. This threshold MCD effect is directly related to spin-orbit effects present at the Fermi edge. We report on the observation of threshold photoemission magnetic circular dichroism (TPMCD) in one-photon and two-photon photoemission (1PPE and 2PPE) at a Pt-capped ultrathin Co wedge grown on Pt(111)/W(110) using femtosecond laser light. TPMCD measurements result in asymmetries continuously increasing with the sample thickness. This indicates that the TPMCD asymmetry is dominantly influenced by the Co bulk properties. At 5 monolayers (ML) asymmetry values of 0.07 % for 1PPE and 0.11 % for 2PPE are derived. The spin reorientation transition is detected at a Co thickness of 5.5 ML. For the magnetically saturated sample the TPMCD does not depend on the orientation of the easy axis. Kerr ellipticities and rotations are measured and compared with the TPMCD data in the framework of optical transfer matrix calculations. The observed TPMCD asymmetry considerably deviates from the behaviour of the complex Kerr angle. Moreover, the TPMCD measurements are referred to Co bulk bandstructure calculations and the influence of a capping layer on the TPMCD asymmetry is discussed