Magnetic circular dichroism in two-photon absorption and depth-resolved magnetic microscopy

The magnetic circular dichroism (MCD) for the 1s→3d two-photon excitation is calculated for a relativistic one-electron atom in an external magnetic field. The MCD in two-photon absorption is of the same order of magnitude as the MCD for the 2p→3d one-photon excitation for the model. Because the MCD in one-photon absorption is well known in nature, this indicates that the MCD in two-photon absorption should be observable experimentally for real magnetic materials. It is suggested to combine the MCD effect with the well-established two-photon microscopy in the infrared and optical regime to establish a depth-resolved magnetic microscopy, with interesting potential applications for magnetic semiconductors or biological systems with paramagnetic centers.