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CATEGORIES:Condensed Matter Physics Seminars
SUMMARY:Domain wall dynamics in a near-Ising ferromagnetic
chain CoCl2*2D2O - Ursula Bengaard Hansen\, Insti
tut Laue-Langevin (ILL)\, Grenoble\, France.
DTSTART:20210423T130000Z
DTEND:20210423T140000Z
UID:TALK4571AT
URL:/talk/index/4571
DESCRIPTION:In this presentation\, I will discuss the magnetic
excitations of a near-Ising ferromagnet in a long
itudinal field. The near Ising ferromagnetic chain
has a characteristic excitation spectrum. In zero
field\, the elementary excitations are clusters o
f overturned spins\, in a pure Ising system the ex
citation energy of these clusters are degenerate a
nd hence independent of the number of flipped spin
s\, the cost of creating a spin cluster comes only
from the domain walls at either end of the cluste
r. This degeneracy can be lifted by inter-chain in
teractions\, non Ising terms in the Hamiltonian or
magnetic fields. It has been proposed\, that the
dynamics of the domain walls of the cluster excita
tions in the presence of a longitudinal magnetic f
ield\, can be interpreted as a magnetic analogue o
f electronic Bloch Oscillations [1]\, which is the
phenomena where a charged particle in a periodic
lattice starts to oscillate when a constant electr
ic field is applied. It has been predicted [2] tha
t the signatures of these Magnetic Bloch Oscillati
ons may be observed using inelastic neutron scatte
ring.\n \nWe have studied the dynamic behaviour of
the cluster excitations in CoCl2.2D2O at the MACS
neutron spectrometer [3]. Here I will present ou
r results and how we are able to account for the d
ifferent features in the excitation spectrums usin
g a Random-Phase Approximation [4]\, that also acc
ounts for the non one-dimensional magnetic interac
tions that are nevertheless still present in CoCl2
.2D2O.\n \n[1] F. Bloch\, Zeitschrift für Physik 5
2\, 555 (1929) [2] S. Shinkevich and O. Syljuåsen\
, PRB 85\, 104408 (2012) [3] U. B. Hansen\, arXiv
preprint arXiv:1906.11554\, 2019 [4] J. Jensen\,
PRB\, 97(2)\, 024423 (2018)
LOCATION:https://bham-ac-uk.zoom.us/j/83190378684?pwd=ZzRIK
1VFMGZCc0FCT3dkQnN4QStCZz09
CONTACT:Mingee Chung
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