Complex magnetic phase in submonolayer Fe stripes on Pt(997)

Abstract

Kuhnke, K.; Repetto, D.; Sessi, V.; Wahl, Peter; Buchsbaum, A.; Varga, P.; Gardonio, S.; Carbone, C.; Krishnakumar, S. R.; Gambardella, P.; Komelj, M.; Singer, R.; Fähnle, M.; Fauth, K.; Schütz, G.; Enders, Axel; and Kern, K., "Complex magnetic phase in submonolayer Fe stripes on Pt (997) Correlations between magnetism and morphology of iron nanostructures of monatomic height on Pt͑997͒ substrates are studied using x-ray magnetic circular dichroism as well as scanning tunneling microscopy and helium scattering. A drastic collapse of the average magnetization by more than a factor of 4 is observed when increasing the iron coverage from 0.1 to 0.2 ML. This effect goes along with a softening of the magnetic anisotropy energy and a gradual reorientation of the magnetic easy axis from in plane to out of plane. The experimental findings together with electronic density-functional calculations suggest the formation of a complex magnetic phase in corrugated rim regions of Fe islands, leading to both ferromagnetic and antiferromagnetic exchange couplings of Fe moments depending on their various local bonding configurations.

Magnetic surface nanostructures

“…At higher substrate temperatures, the step edges represent penetrable defects for adatoms to enter the surface layer of the substrate. This has been exploited, for instance, to form 2D FePt surface alloys [57,8].…”

“…Figure 4 illustrates some typical examples. Since the local atomic environments in these structures are all different from each other, they represent ideal model systems to study coordination and size effects on magnetism during the crossover from zero to two dimensions [8]. The interaction between Fe and the Pt substrate has a decisive influence on the magnetism and can be exploited to tune the magnetic properties of low-dimensional structures, discussed in section 4.…”

“…RKKY and magnetostatic interactions can extend over several tens of nm. Bottom: examples of structures, displaying characteristic phenomena as above: spin frustration in Cr trimers [6], Friedel oscillations in Cu (111) around Co adatoms [7], chains of Fe atoms on Pt(997) [8], Fe clusters on Pt(111) [9], magnetic vortex in an Fe island [10] and magnetic domains in 3 ML Fe/Cu(100) [11] (from left).…”

Complex magnetic structure of clusters and chains of Ni and Fe on Pt(111)

“…Several open questions involving the relationship between chemical and magnetic order in such nanostructures remain. Correlations between magnetism and atomic structure have also been experimentally investigated in Fe-Pt monolayer alloys13 and corrugated Fe islands1314 on Pt surfaces, suggesting the formation of a complex magnetic phase, due to the influence of the local environment.…”

“…This study has been motivated by an interesting discussion on the role of the mediating Pt atoms on the stable magnetic configurations of these nanostructures121314. Here, the goal is the possibility of controlling and tailoring complex magnetic configurations on the atomic scale, by exploring the presence of magnetic frustrations.…”