Advances of Photothermal Microscopy of Composite Magnetoelectric Nanolayers Using Laser Heterodyne Probe

A theoretical solution advances the potential for photothermal mi¬croscopy of nanostructured composite magnetoelectrics and high-temperature su¬perconductors. Photothermal displacement (PTD) is a sensitive effect employed as a fingerprint of the physical and structural properties of a variety of prospective materials. Thermal-diffusion model is developed for the general case including opaque and also transparent probes. Laser double-heterodyne technique is em¬ployed to improve the resolution of PTD measurement. The excessive noise is eliminated to the level viable to detect structural inhomogeneities and thickness of nanolayers up to 0.1nm. The method is applicable to nanolayers deposited on opaque substrates, as well, transparent substrates with large gradient of refrac¬tive index of the interface. Very good agreement between experimental results and theoretical prediction is achieved. The developed laser scheme is particularly feasible for non-destructive measurements of samples at operational conditions and restricted access.