Resolving antiferromagnetic states in magnetically coupled amorphous Co-Si-Si multilayers by soft x-ray resonant magnetic scattering

Abstract

Soft x-ray resonant magnetic scattering ͑SXRMS͒ has been used to probe the interlayer coupling in amorphous ferromagnetic/semiconductor multilayers. It is shown that the ͓Co 73 Si 27 ͑50 Å͒ / Si ͑30 Å͔͒ system exhibits an antiferromagnetic ͑AF͒ coupling at low fields. Moreover, another aspect of SXRMS effect is reported. Using circularly polarized photons, a shift in the AF order Bragg peaks' position is observed and related to two opposite AF states with the spin direction longitudinally aligned. As a consequence, the sensitivity of SXRMS to AF domains having the same spin axis but opposite senses is shown. A physical explanation for the origin of this effect is provided in terms of magnetic-resonant-refraction corrections to Bragg's angle, taking into account the phase shifts between layers with opposite magnetization directions at different in-depth positions. Numerical simulations are performed that reproduced the experimental observations.

Using small-angle scattering to guide functional magnetic nanoparticle design

“…However, XRMS is nowadays mostly used in the so X-ray range to study nanoscale magnetic structures, such as magnetic multilayers, [312][313][314][315][316][317] magnetic domains in ferromagnetic thin lms, [318][319][320][321][322][323][324][325][326] noncollinear spin textures in magnetic thin lms, [327][328][329][330][331][332] magnetic ordering in antiferromagnetic system 333 and exchange-coupled magnetic layers. 334,335 When tuned to the Co and Fe-L 3 edges, the X-ray wavelength is around l ¼ 1.6 nm and 1.75 nm, respectively (so X-rays).…”

Resonant Soft X-ray Reflectivity in the Study of Magnetic Properties of Low-Dimensional Systems

“…Strain and epitaxy conditions may change the crystal structure of elemental metals, giving rise to artificially tailored magnetic properties that are not available in the corresponding bulk materials. RSXMR has been applied in prototypical studies: for example, to resolve the spin orientation structure of ultrathin fcc Fe films on Cu(001) [93,94]; to resolve the induced moment in uranium in U/Fe multilayers [95]; to probe the interlayer coupling in ferromagnetic/semiconductor multilayers [96]; and to measure the value of the magnetic moment, its orientation, and depth profiles in Fe/C [97], Gd/Fe [98][99][100], and Co/Mg [101] multilayers or in Cu/Fe/Cu trilayers on a semiconductor [102]. Carlomagno et al [103] investigated, through resonant X-ray reflectivity, the structural and magnetic properties of a MgO/Co/MgO trilayer, evidencing difference in Co oxidation and roughness between the bottom (Co on MgO) and top (MgO on Co) interfaces, which was reflected in an asymmetric magnetization profile for the Co layer.…”

Standing wave approach in the theory of X-ray magnetic reflectivity

“…From ( 35), (36) we get the reflectivity matrix amplitude for a single ultrathin layer in the following form:…”

“…X-ray resonant magnetic reflectivity (XRMR) gives unique elemental and spatially selective information about magnetic ordering in multilayer films (see e.g. [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]). In these experiments two circular or two linear polarizations of synchrotron radiation are used and the asymmetry ratio relative the polarization state of the incident radiation is measured.…”