ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

szept. 23. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba

Oroszlány László (ELTE Komplex Rendszerek Fizikája Tanszék):
Electrically driven singlet-triplet transition in triangulene spin-1 chains

In stark contrast to one-dimensional spin-1/2 systems, spin-1 models, as
conjectured by Haldane, have a characteristic gap in their excitation
spectrum. Localized to the edges of finite spin-1 chains, topologically
protected spin-1/2 edge modes appear, endowing the system with a fourfold
degenerate ground state. This degenerate subspace might be used to
implement a singlet-triplet spin-qubit. However, manufacturing
low-dimensional spin-1 systems is notoriously difficult. Typically many
such chains are synthesized in organometallic compounds, involving heavy
elements. In these systems inter-chain interactions and spin-orbit coupling
are non-negligible, thus complicating the picture. Recently, graphene
triangulene chains have been synthesized and their magnetic response has
been analyzed[1], which can be considered true realizations of
one-dimensional spin-1 chains.
We determined [2] the exchange bilinear and biquadratic constants of the
triangulene chains by calculating two-spin rotations in the spirit of the
magnetic force theorem. We then analyzed open ended chains with an odd
number of triangulenes, whose edge states pair up forming a triplet ground
state. We proposed three experimental approaches to trigger and control a
singlet-triplet spin transition. Two of these methods are based on applying
mechanical distortion to the chain. We finally showed that the transition
can be controlled efficiently by the application of an electric field.

[1]:  Mishra et al, Nature 598, 287 (2021)
[2]:  G Martínez-Carracedo, L Oroszlány, A García-Fuente, L Szunyogh, J
Ferrer, arXiv:2207.13683 (2022)


Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor