TY - JOUR
T1 - Modulated and monotonic monolayer-magnetism in hetero-epitaxial Fe on Cu(001)
AU - Paul, Amitesh
N1 - Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/7/1
Y1 - 2020/7/1
N2 - We have combined two complementary techniques, element sensitive ex situ X-ray magnetic circular dichroism (XMCD) and in situ polarized neutron reflectivity (i-PNR), to determine the values of evolving magnetic moments obtained from a low symmetry system of hetero-epitaxial Fe monolayers (MLs), as a function of thickness. The samples were grown by magnetron sputtering on face-centered-cubic (fcc) Cu(001)/Si(001). Within experimental errors, we found a corroboration of the modulated moments from the XMCD and of the magnetic anisotropies from magnetization measurements with those obtained earlier from layer-by-layer i-PNR measurements. The modulation was attributed to initial island-like growth morphology assisted monolayer-magnetism during sputtering. Furthermore, analyzing the depth sensitive i-PNR profile of a bulk-like film, we developed a model characterized by monotonic magnetism involving collinear spins. The model is further described by a higher magnetization for the deeper layers, which decreases gradually for the upper layers before attaining saturation at its bulk value within a few MLs. This model contradicts the earlier proposed non-collinear model involving antiferromagnetic units, thus clarifying the long standing ambiguity in the coverage regime. The results have been compared with those existing, following the theoretical parameterized tight-binding model with satisfactory agreement. This study distinguishes the variation of monolayer-magnetism owing to the growth morphology from the layer-by-layer investigation vis-à-vis depth-profiling of bulk-like film. At the same time, it also promises the general possibility of depth-profiling using i-PNR in other complex multilayered systems on high flux neutron sources.
AB - We have combined two complementary techniques, element sensitive ex situ X-ray magnetic circular dichroism (XMCD) and in situ polarized neutron reflectivity (i-PNR), to determine the values of evolving magnetic moments obtained from a low symmetry system of hetero-epitaxial Fe monolayers (MLs), as a function of thickness. The samples were grown by magnetron sputtering on face-centered-cubic (fcc) Cu(001)/Si(001). Within experimental errors, we found a corroboration of the modulated moments from the XMCD and of the magnetic anisotropies from magnetization measurements with those obtained earlier from layer-by-layer i-PNR measurements. The modulation was attributed to initial island-like growth morphology assisted monolayer-magnetism during sputtering. Furthermore, analyzing the depth sensitive i-PNR profile of a bulk-like film, we developed a model characterized by monotonic magnetism involving collinear spins. The model is further described by a higher magnetization for the deeper layers, which decreases gradually for the upper layers before attaining saturation at its bulk value within a few MLs. This model contradicts the earlier proposed non-collinear model involving antiferromagnetic units, thus clarifying the long standing ambiguity in the coverage regime. The results have been compared with those existing, following the theoretical parameterized tight-binding model with satisfactory agreement. This study distinguishes the variation of monolayer-magnetism owing to the growth morphology from the layer-by-layer investigation vis-à-vis depth-profiling of bulk-like film. At the same time, it also promises the general possibility of depth-profiling using i-PNR in other complex multilayered systems on high flux neutron sources.
UR - http://www.scopus.com/inward/record.url?scp=85082115540&partnerID=8YFLogxK
U2 - 10.1016/j.jmmm.2020.166701
DO - 10.1016/j.jmmm.2020.166701
M3 - 文章
AN - SCOPUS:85082115540
SN - 0304-8853
VL - 505
JO - Journal of Magnetism and Magnetic Materials
JF - Journal of Magnetism and Magnetic Materials
M1 - 166701
ER -