Ultra-high density memory device

Abstract

A ultra-high density memory device utilizing a photoinductive ferromagnetic thin film. A photoinductive ferromagnetic thin film is formed on a GaAs substrate, and a tip is arranged so as to face the photoinductive ferromagnetic thin film. The GaAs substrate is disposed on an xyz scanner, and the three-dimensional positional relationship between the GaAs substrate and the tip is changed by the xyz scanner. Blue light is radiated onto the thin film in order to make the magnetization orientation of molecules uniform. Through application of a relatively high voltage, a relatively large current is caused to flow between the tip and the substrate, so that randomization of the magnetization orientation of molecules of the photoinductive ferromagnetic thin film; i.e., writing operation is carried out. Also, through uniform radiation of circular polarized light onto the GaAs substrate and application of a relatively low voltage, tunneling current is caused to flow between the tip and the substrate, which tunneling current changes in accordance with the magnetization orientation of molecules of the photoinductive ferromagnetic thin film. Through detection of the tunneling current, the magnetization orientation of molecules of the photoinductive ferromagnetic thin film can be detected.