Depth Magnetization Profile of a Perpendicular Exchange Coupled System by Soft-X-Ray Resonant Magnetic Reflectivity

Abstract

The magnetic profile across the interface of a perpendicular exchange coupled [NiO/CoO]3/Pt-Co/Pt(111) system is investigated. The magneto-optic Kerr effect reveals a strong coupling between the antiferromagnetic (AFM) oxide and the ferromagnetic (FM) Pt-Co layer, by an increasing coercivity and a rotation of the easy magnetization axis of the FM layer along the AFM spins. Soft x-ray resonant magnetic reflectivity is used to probe the spatial distribution of the out-of-plane magnetization inside the oxide above its ordering temperature. It extends over 1 nm and exhibits a change of sign.

Depth-resolved magnetization distribution in ultra thin films by soft X-ray resonant magnetic reflectivity

“…Since in a SXRMR experiment the magnetic contrast is linked to the magnetic moment via the result of the sum rules applied to the XMCD signal used [6], the differences can be a source of uncertainties in the determination of absolute magnetic moments. They do not affect the potential of SXRMR to determine the film magnetization profile [20,28]. In the present study, f and m are determined from the measurements carried out on a reference Fe film, for which sum rules yield a magnetic moment of 2.1μ B [21].…”

“…Typically, X-ray resonant magnetic scattering is carried out by analyzing the energy dependence of the reflectivity at different incident angles or scattering vector values [10][11][12][13][14], whereas recently strong interest in the analysis of the angular dependence of the reflectivity has emerged [15][16][17][18][19]. This turns out to be particularly relevant in the soft X-ray range where the reflectivity, measured at large scattering angles, is sensitive to the out-of-plane magnetization [20]. Furthermore, soft X-ray resonant magnetic reflectivity (SXRMR) has been shown to resolve the magnetic structure along the growth axis with in-plane and perpendicular components [21].…”

“…The out-of-plane magnetization is probed by magnetizing the sample perpendicular to the sample plane (called here "polar" configuration). Up to now this condition has been realized by moving a permanent magnet close to the sample surface followed by data collection in remanence [20,21,28]. In this case, Ip and Im are obtained by reversing the X-ray helicity.…”

The influence of surface roughness in X-ray resonant magnetic reflectivity experiments

“…Because the variation of the magnetic moment due to the breaking of crystalline symmetry at surface or interface extends for a depth of few unit cells (a unit cell in perovskite oxides typically has a lattice parameter ∼4Å), for a spectroscopic investigation of the magnetism, a probe with a wavelength comparable to this dimension and sensitive to atomic magnetic moments is needed. The two most common techniques for measuring magnetic a e-mail: verna@tasc.infm.it depth profiles on the unit-cell scale are reflectivity measurements by polarized neutrons [3,4] and X-rays in resonance condition with the magnetic species [5][6][7][8][9][10]. The advantage of X-rays produced e.g.…”

RASOR: An advanced instrument for soft x-ray reflectivity and diffraction

“…Schäfers et al 16 used multilayer diffraction to develop a soft x-ray polarimeter to detect the polarization state of soft x-ray beams. Soft x-ray reflectivity measurements have facilitated a number of high profile papers on magnetic multilayer materials [17][18][19] that have potential impact in novel device manufacture.…”