title: Confined crystals of the smallest phase-change material.
abstract: The demand for high-density memory in tandem with limitations imposed by the minimum feature size of current storage devices has created a need for new materials that can store information in smaller volumes than currently possible. Successfully employed in commercial optical data storage products, phase-change materials, that can reversibly and rapidly change from an amorphous phase to a crystalline phase when subject to heating or cooling have been identified for the development of the next generation electronic memories. There are limitations to the miniaturization of these devices due to current synthesis and theoretical considerations that place a lower limit of 2 nm on the minimum bit size, below which the material does not transform in the structural phase. We show here that by using carbon nanotubes of less than 2 nm diameter as templates phase-change nanowires confined to their smallest conceivable scale are obtained. Contrary to previous experimental evidence and theoretical expectations, the nanowires are found to crystallize at this scale and display amorphous-to-crystalline phase changes, fulfilling an important prerequisite of a memory element. We show evidence for the smallest phase-change material, extending thus the size limit to explore phase-change memory devices at extreme scales.
authors.affiliation: Advanced Technology Institute, University of Surrey , Guildford, GU2 7XH, United Kingdom.
authors.forename: Cristina E
authors.initials: CE
authors.lastname: Giusca
authors.forename: Vlad
authors.initials: V
authors.lastname: Stolojan
authors.forename: Jeremy
authors.initials: J
authors.lastname: Sloan
authors.forename: Felix
authors.initials: F
authors.lastname: Börrnert
authors.forename: Hidetsugu
authors.initials: H
authors.lastname: Shiozawa
authors.forename: Kasim
authors.initials: K
authors.lastname: Sader
authors.forename: Mark H
authors.initials: MH
authors.lastname: Rümmeli
authors.forename: Bernd
authors.initials: B
authors.lastname: Büchner
authors.forename: S Ravi P
authors.initials: SR
authors.lastname: Silva