Stable and Metastable Kinetic Ferromagnetism on a Ring
Seminars
Seminar “Theory of Condensed Matter”
Date and Time: Tuesday, 7 July 2020, at 4:00 PM
Venue: Online conference in Zoom, Bogoliubov Laboratory of Theoretical Physics
Seminar topic: «Stable and Metastable Kinetic Ferromagnetism on a Ring»
Authors: Ilya Ivantsov (BLTP), Hernan B. Xavier, Alvaro Ferraz, and Evgenii Kochetov
Speaker: Ilya Ivantsov
Abstract:
Performing an exact diagonalization of the effective spin problem, a ferromagnetic ground state of kinetic origin is shown to emerge in a system of N strongly correlated electrons on an L-site ring (L > N). A problem of N constrained spinfull electrons on an L-site ring is argued to reduce to that of the spinless fermions with an effective flux threading through the ring. This phenomenon is brought about by the quantum necklace statistics originated by the no double occupancy constraint leading to a fractional shifted electron momentum quantization. As a consequence of such special energy level distribution, the kinetic ferromagnetism is stable only for N=3. For odd N>3 the fully polarized FM state energy is only a local minimum but it is protected by a finite energy barrier that inhibits one spin-flip processes. The metastable ferromagnetic state survives perturbations of small magnitude opening up a possibility of being experimentally observed by appropriate tuning of interdot tunnelling amplitudes in currently available quantum dot arrays.