Magnetoelectric effect in Cr$_{2}$O$_{3}$ thin films

Magnetoelectric materials experienced a recent revival as promising components of novel spintronic devices [1, 2, 3]. Since the magnetoelectric (ME) effect is relativistically small in traditional antiferromagnetic compounds like Cr$_{2}$O$_{3}$ (max. $\alpha _{zz}\approx $4ps/m ) and also cross- coupling between ferroic order parameters is typically small in the modern multiferroics, it is a challenge to electrically induce sufficient magnetization required for the envisioned device applications. A straightforward approach is to increase the electric field at constant voltage by reducing the thickness of the ME material to thin films of a few nm. Since magnetism is known to be affected by geometrical confinement thickness dependence of the ME effect in thin film Cr$_{2}$O$_{3 }$is expected. We grow (111) textured Cr$_{2}$O$_{3}$ films with various thicknesses below 500 nm and study the ME effect for various ME annealing conditions as a function of temperature with the help of Kerr-magnetometry. [1] P. Borisov et al. Phys. Rev. Lett. \textbf{94}, 117203 (2005). [2] Ch. Binek, B.Doudin, J. Phys. Condens. Matter \textbf{17}, L39 (2005). [3] R. Ramesh and Nicola A. Spaldin 2007 \textit{Nature Materials} \textbf{6} 21.