Synopsis: Twisting left and right gives logic another turn

Calculations indicate that germanium telluride nanoplatelets above a certain size should exhibit a reversible toroidal spin ground state, control over which could be useful for computing applications.
Synopsis figure
Illustration: Durgun et al., Phys. Rev. Lett. (2009)

Germanium telluride can be thermally switched between a metastable crystalline phase and an amorphous state. In its crystalline form, it is a ferroelectric with spontaneous polarization. This structural transition would seem promising for data storage, through switching the crystalline (and hence ferroelectric) state on and off. However, applications involving germanium telluride have not been realized, primarily due to its high concentration of intrinsic vacancies.

In addition to crystal structure, size also affects ferroelectric properties. In view of this, Engin Durgun and colleagues at Université de Liège and at the Université Catholique de Louvain, both in Belgium, have performed first-principle calculations on germanium telluride nanoplatelets. For platelets with a diameter larger than 2.7 nm, they predict the emergence of polarization vortices that should give rise to a ferrotoroidic ground state, with a spontaneous and reversible toroidal moment. The authors predict that the inhomogeneous strain would play a role in stabilizing the spiral. In addition to fundamental interest, this effect, together with the transition from crystalline to amorphous structure, can be used to record three spin states (right-hand spiral, left-hand spiral, and amorphous/off), which could be used for ternary logic. – Daniel Ucko


More Features »


More Announcements »

Subject Areas


Previous Synopsis

Atomic and Molecular Physics

Imaging molecular breakup

Read More »

Next Synopsis

Statistical Physics

Gravity organizes sediment

Read More »

Related Articles

Synopsis: Straining After Quantum Dots
Semiconductor Physics

Synopsis: Straining After Quantum Dots

The positions of quantum dots inside a microstructure can be determined by monitoring how an applied strain affects the dots’ photoluminescence.   Read More »

Viewpoint: A New Twist on Relativistic Electron Vortices

Viewpoint: A New Twist on Relativistic Electron Vortices

Two studies explore the properties of vortices formed by electrons that travel at relativistic speeds. Read More »

Focus: Nanochannel Could Separate Mixed Fluids
Fluid Dynamics

Focus: Nanochannel Could Separate Mixed Fluids

Calculations show that capillary forces affecting a fluid mixture flowing through a nanochannel could be used to separate the mixture. Read More »

More Articles