Spin-Flop Ordering from Frustrated Ferro- and Antiferromagnetic Interactions: A Combined Theoretical and Experimental Study of a $\mathrm{Mn}/\mathrm{Fe}(100)$ Monolayer

The occurrence of a noncollinear magnetic structure at a Mn monolayer grown epitaxially on Fe(100) is predicted theoretically, using spinor density-functional theory, and observed experimentally, using x-ray magnetic circular dichroism (XMCD) and linear dichroism (XMLD) spectroscopies. The combined use of XMCD and XMLD at the Mn-absorption edge allows us to assess the existence of ferromagnetic and antiferromagnetic order at the interface, and also to determine the moment orientations with element specificity. The experimental results thus obtained are in excellent agreement with the magnetic structure determined theoretically.

Figure 1

Top panel: total energies of the FM, AFM, FI, and NC structures relative to the FM structure. Bottom panel: magnitude of the atomic magnetic moments in the various structures. For the FI structure $\uparrow \uparrow$ and $\uparrow \downarrow$ indicate the Mn atom with magnetic moment parallel and antiparallel to the underlying Fe atoms, respectively.

Figure 2

Schematic view of the $\mathrm{Mn}/\mathrm{Fe}$ magnetic interface.

Figure 3

(a) XMCD data at the $L_{2,3}$ edges for 1 ML of Mn. (b) Mn $L_{2,3}$ x-ray-absorption spectroscopy for 1 ML of Mn as a function of the angle $\theta$ between $\mathit{E}$ and the surface normal. The difference spectra are plotted at the bottom.

Figure 4

XMLD effect (a) for the polar and (b) for the azimuthal rotations. The intensity ratio of the Mn $L_2$ double peak structures is used to measure the intensity of the effect.

Figure 5

(a),(b) Simulation of the absorption spectra for the two polarization directions after suitable broadening. (c) Comparison between the simulated and the experimental XMLD. (d) Simulated $P_{\mathrm{I}}/P_{\mathrm{II}}$ intensity ratio.