S. Soriano

Clamping effects in the Al2O3(112¯0)∕Nb(110)∕Eu(110) epitaxial system

In-plane and out-of-plane lattice parameters of Nb and Eu have been measured as a function of temperature between 10 and 300 K in the Al2O3(112¯0)∕Nb(110)∕Eu(110) epitaxial system. It is shown that the Nb lattice is clamped in the growth plane to the sapphire substrate, in the whole temperature range. On its own, the Eu lattice is totally free to expand isotropically above a clamping temperature Tcl, below which in-plane parameters also freeze to an almost constant value. This well-defined clamping temperature strongly depends on the Eu thickness and likely is related to the thermal mobility of interface defects.

Magnetic configuration in (110) Eu films

(110) europium films exhibit an atypical magnetic arrangement at low temperature, characterized by a low magnetization value from macroscopic magnetization measurements. An accurate analysis of the temperature and magnetic field range, where this specific configuration is stabilized, has shown that it is favored by a small Eu thickness. A two-helices configuration with propagation vectors along [100] and [010] may explain this low magnetization state.

Clamping effect on the magnetic behavior of europium epitaxial thin films

Epitaxial thin films of europium experience significant strains when deposited on a sapphire substrate with a niobium buffer. We demonstrate that the relative population of the magnetic domains is affected, in particular, in the presence of a slight tilt of the film growth axis relative to the substrate. The application of a magnetic field further modifies the population of the domains giving rise to unusual irreversible effects. These results could help to elucidate the magnetoelastic properties of bulk europium, which are still unknown.

Helical magnetic structures in epitaxial [110] Eu films

In this paper, we investigate how the symmetry breaking, the lattice clamping and eventually the epitaxial strains in a thin film may affects the magnetic arrangement.