Theoretical study of enhanced magneto-optical Kerr effect at Fe/insulator interfaces

Gu, B.

Gu, B.

Magneto-optical Kerr effect (MOKE) is the phenomenon in which the light reflected from a magnetized material has a rotated plane of polarization. The MOKE originates from spin-orbit coupling in materials, and the effect has played a significant role in the rapidly developing field of spintronics. For applications to magneto-optical devices, a large MOKE is required. By density functional theory calculations, we have found an enhanced MOKE at Fe/insulator interfaces. Our study indicates that interfacial Fe atoms in the Fe films have a low-dimensional nature, which causes the following two effects: (1) The diagonal component of the optical conductivity decreases dramatically because the hopping integral for electrons between Fe atoms is suppressed by the low dimensionality. (2) The off-diagonal component of the optical conductivity does not change at low photon energies, but it is enhanced at photon energies around 2 eV, where we obtain enhanced orbital magnetic moments and spin-orbit correlations for the interfacial Fe atoms. Our findings indicate an efficient way to enhance the effect of spin-orbit coupling at metal/insulator interfaces without using heavy elements.