The magnetization reversal process within the first two iron layers at the Fe/GaAs(001) interface is found to be different and independent from the Fe thin film bulk as measured by magnetic second-harmonic generation and magneto-optical Kerr effect. The interface magnetization is largely noncollinear from the bulk with an abrupt magnetic boundary and an anisotropic exchange coupling stiffness, weak interlayer coupling but relatively strong intralayer stiffness. In contrast, Fe/GaAs(110) exhibits a rigid coupling between interface and bulk magnetization suggesting that the interfacial bonding structure can dramatically change the nature of the exchange coupling. Moreover, the uniaxial magnetic anisotropy in Fe/GaAs(001) extends from the interface to the first 5 nm in the Fe film and is induced by stress. These results are also relevant to other magnetic/nonmagnetic interfaces with abrupt chemical bond structures.

The dependence of the intrinsic Gilbert damping parameter α0 on the spin-orbital coupling strength ξ is investigated in L10 ordered FePd1−xPtx films by time-resolved magneto-optical Kerr effect measurements and spin-dependent ab initio calculations. Continuous tuning of α0 over more than one order of magnitude is realized by changing the Pt/Pd concentration ratio showing that α0 is proportional to ξ2 as changes of other leading parameters are found to be negligible. The perpendicular magnetic anisotropy is shown to have a similar variation trend with x. The present results may facilitate the design and fabrication of new magnetic alloys with large perpendicular magnetic anisotropy and tailored damping properties.

The ferromagnet/oxide interface is key to developing emerging multiferroic and spintronic technologies with new functionality. Here we probe the Fe/MgO interface magnetization, and identify a new exchange bias phenomenon manifested only in the interface spin system, and not in the bulk. The interface magnetization exhibits a pronounced exchange bias, and the hysteresis loop is shifted entirely to one side of the zero field axis. However, the bulk magnetization does not, in marked contrast to typical systems where exchange bias is manifested in the net magnetization. This reveals the existence of an antiferromagnetic exchange pinning layer at the interface, identified here as FeO patches that exist even for a nominally ‘clean’ interface. These results demonstrate that atomic moments at the interface are non-collinear with the bulk magnetization, and therefore may affect the net anisotropy or serve as spin scattering sites. We control the exchange bias magnitude by varying the interface oxygen concentration and Fe–O bonding.

Pronounced spin precessions are observed in Fe films grown on n-doped GaAs(001) with a tailored Schottky interface under low-energy ultrafast laser excitation, more than two orders of magnitude smaller than typically required in heat-induced excitation. Pump wavelength dependence of the precession amplitude shows that the fast drift of the optically excited free carriers in the narrow depletion layer of GaAs is the key mechanism to generate the significant transient magnetic field triggering spin precessions.

Spin angular momentum transfer into an antiferromagnetic (AFM) insulator is observed in a single-crystalline Fe/CoO/MgO(001) heterostructure by time-resolved magneto-optical Kerr effect. The transfer process is mediated by the Heisenberg exchange coupling between Fe and CoO spins. Spin angular momentum transfer to ordered AFM spins is independent of the external magnetic field and enhances the spin precession damping in Fe, which remains nearly invariant with temperature.