Non-melting super-resolution near-field apertures in Sb-Te alloys

The super-resolution near-field structure permits the formation of short-lived subdiffraction limit apertures that channel electromagnetic energy at the aperture boundary. This effect is commonly observed when a laser is focused onto a thin film of Sb based material. The aperture formation within Sb, Sb₂ Te₃, Sb₂ Te, and SbTe is investigated by time resolved optical pump-probe techniques and found to occur without melting. Ab initio modeling has shown a threshold-like change in the optical properties below the melting temperature which leads to the formation of a near-field aperture. This threshold is shown to be a consequence of thermally induced misalignment of p-type bonding.