A new ultra-high-vacuum variable temperature and high-magnetic-field X-ray magnetic circular dichroism facility at LNLS

Abstract

X-ray magnetic circular dichroism (XMCD) is one of the most powerful tools for investigating the magnetic properties of different types of materials that display ferromagnetic behavior. Compared with other magnetic-sensitive techniques, XMCD has the advantage of being element specific and is capable of separating the spin and magnetic moment contributions associated with each element in the sample. In samples involving, for example, buried atoms, clusters on surfaces or at interfaces, ultrathin films, nanoparticles and nanostructures, three experimental conditions must be present to perform state-of-the-art XMCD measurements: high magnetic fields, low temperatures and an ultra-high-vacuum environment. This paper describes a new apparatus that can be easily installed at different X-ray and UV beamlines at the Brazilian Synchrotron Light Laboratory (LNLS). The apparatus combines the three characteristics described above and different methods to measure the absorption signal. It also permits in situ sample preparation and transfer to another chamber for measurement by conventional surface science techniques such as low-energy electron diffraction (LEED), reflection high-energy electron diffraction (RHEED), X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD). Examples are given of XMCD measurements performed with this set-up on different materials.

Patterning Quasi-Periodic Co 2D-Clusters underneath Graphene on SiC(0001)

“…XMCD is a well-established magnetic-element/chemical specific technique which is based in the measurement of the X-ray absorption spectroscopy (XAS) for core-levels using circularly polarized light . The measurements were performed using the planar grating monochromator beamline (PGM) at the Brazilian Synchrotron Light Source (LNLS) using an UHV-XMCD chamber with facilities for sample heating, cooling, and application of moderate magnetic field for absorption measurements in the total electron yield mode. An equivalent sample to the one presented in Figures and was prepared with cobalt intercalation displaying the same behavior of the previous samples as detected by XPS.…”

A new soft X-ray magnetic circular dichroism facility at the BSRF beamline 4B7B

“…The permanent magnet should be reversed manually or mechanically to switch the field, but it is still used by some groups [15,16]. Electromagnets are widely used by several groups in a variety of ways [17][18][19][20][21][22]. The main advantage of an electromagnet over a permanent magnet is that the direction and intensity of the magnetic field can be automatically manipulated.…”

Surface magnetic contribution in zinc ferrite thin films studied by element- and site-specific XMCD hysteresis-loops

“…X-ray absorption spectroscopy (XAS) experiments at L 2,3 edges of iron were performed at room temperature at PGM beamline [19] of Brazilian Synchrotron Light Laboratory-LNLS (Campinas, Brazil) using circularly polarized light with a degree of circular polarization around 80%. The absorption data were collected in the TEY mode.…”