We report the results of the electrical switching and thermal studies performed on the bulk ${\mathrm{Al}}_{20}{\mathrm{Ge}}_x{\mathrm{Te}}_{80-x}$ chalcogenide glasses which are a sequel to similar experiments on the ${\mathrm{Al}}_{20}{\mathrm{As}}_x{\mathrm{Te}}_{80-x}$ glasses to ascertain the role of the crosslinking elements Ge and As in memory and threshold switching glasses. Anomalously large switching fields are seen for relatively smaller crystallization temperatures contradicting the thermal model for memory switching phenomenon. The present findings when viewed in conjunction with the data on other glassy alloys suggest that chemical ordering, the well known topological feature in chalcogenide glasses, influences the type of switching. A simple chemical bond and electronic band picture is developed to comprehend the results.

• Received 18 August 1999

DOI:https://doi.org/10.1103/PhysRevB.63.092203