Electronic structure and magnetic properties of epitaxial FeRh(001) ultrathin films on W(100)

Epitaxial FeRh(100) films (CsCl structure, $\sim 10\text{ML}$ thick), prepared in situ on a W(100) single-crystal substrate, have been investigated via valence band and core-level photoemission. The presence of the temperature-induced, first-order, antiferromagnetic to ferromagnetic $\left(\text{AF}\to \text{FM}\right)$ transition in these films has been verified via linear dichroism in photoemission from the $\text{Fe}3p$ levels. Core-level spectra indicate a large moment on the Fe atom, practically unchanged in the FM and AF phases. Judging from the valence band spectra, the metamagnetic transition takes place without substantial modification of the electronic structure. In the FM phase, the spin-resolved spectra compare satisfactorily to the calculated spin-polarized bulk band structure.

Figure 1

(Color online) (a) LEED patterns from W(001) (top, $E_{\text{ph}}=54\text{eV}$) and from an epitaxial film (10 ML) of FeRh(001) (bottom; $E_{\text{ph}}=57.2\text{eV}$). (b) Photoemission spectra from shallow core levels ($\text{Fe}3p$ and $\text{Rh}4p$) from equiatomic FeRh films, before and after annealing. The spectra from films of Fe and Rh metals are also shown for comparison. (c) Valence-band spectra corresponding to the spectra shown in (b).

Figure 2

(Color online) (a) Linear magnetic dichroism in photoemission from $\text{Fe}3p$ and $\text{Rh}4p$ core levels of an FeRh film in the ferromagnetic phase. Inset shows a blow up of the $\text{Rh}4p$ region. (b) Temperature dependence of the $\text{Fe}3p$ dichroism signal.

Figure 3

(Color online) (a) $\text{Fe}3s$ and $\text{Rh}4s$ core-level spectra from Fe and Rh metals and from equiatomic FeRh alloy in the AF (solid line) and FM (open circles) phases; (b) similar to (a) but for $\text{Fe}3p$ and $\text{Rh}4p$ levels; (c) normal-emission valence-band spectra taken close to the high-symmetry $\Gamma$ and X point.

Figure 4

(Color online) Valence-band spin-resolved spectra in the ferromagnetic phase at the high-symmetry $\Gamma$ and X points that are marked with arrows (up/down: majority/minority). The exchange splitting $\left(\Delta E_{ex}\right)$ is estimated to be around 1.4 eV. See text for details. The clearest feature is perhaps the ${\Delta }_5$ sharp minority state close to the Fermi level ($\sim 0.2\text{eV}$ binding energy) in the spectra.

Figure 5

(Color online) Electronic bands and DOS of ferromagnetic FeRh. Only bands along the $\Delta$ high-symmetry line ($\Gamma \text{-X}$ line) of the fcc BZ are shown, full circles indicate bands of ${\Delta }_1$ or ${\Delta }_5$ symmetries. See text for details.