Tailoring Surfaces and Interfaces is an important issue that is tackled by different ways in our Department, among which : The control of the magnetic anisotropy in thin film elements, adding new functionalities to standard magnetic materials by inducing exchange-bias, and developing new tools for imaging surface electric fielddistributions in magnetic multiferroics.
Surface electric field distribution
Taking advantage of the high-sensitivity of ultraslow electrons (energy < 3eV) to small variations of the electric potential near surfaces, we have demonstrated the possibility of imaging ferroelectric domains with low-energy electron microscopy (LEEM) in the mirror operation mode.
The prospect of inducing an exchange-bias (EB) in magnetic semiconductors (eg. (Mn,Ga)As, GeMn …) or in antiferromagnetic multiferroics (such as BiFeO3) adds an exceptional functionality to these materials.
We have recently demonstrated exchange biasing of self-organized GeMn nanocolumns by oxidized-GeMn caps. The observed exchange-bias is attributed to the exchange coupling at the interface between the ferromagnetic GeMn nanocolumns and the antiferromagnetic MnO-like caps.
Tuning the domain wall orientation in thin magnetic strips using induced anisotropy
The possibility to tune the orientation of in-plane magnetic domains and domain walls (DWs) in narrow ferromagnetic strips is demonstrated. This is achieved by controlling the magnetic anisotropy of the system by using oblique evaporation. In particular, a direct correlation between the imposed uniaxial magnetic anisotropy and the domain wall orientation is found experimentally and confirmed by micromagnetic simulation studies