Phase change writing in a GeSbTe film with scanning near-field optical microscope

Scanning near-field optical microscopy (SNOM) was applied to phase-change (PC) mark writing to investigate the potential of ultrahigh density data storage. GeSbTe, one of the typical PC media, was used as a recording layer. Using a laser diode (LD) with a wavelength of 785 nm as light source, crystalline marks with a minimum size of ∼ 80 nm in diameter were successfully written in the amorphous GeSbTe film with pulse conditions of 5 ms and 0.5 ms and 8.4 mW inside the probe. The detected power in observation of the marks was 102–103 times as high as that in magneto-optical (MO) observation.