TY  - JOUR
AU  - Sallermann, Moritz
AU  - Jónsson, Hannes
AU  - Blügel, Stefan
TI  - Stability of hopfions in bulk magnets with competing exchange interactions
JO  - Physical review / B
VL  - 107
IS  - 10
SN  - 2469-9950
CY  - Woodbury, NY
PB  - Inst.
M1  - FZJ-2023-01402
SP  - 104404
PY  - 2023
AB  - Magnetic hopfions are string-like three-dimensional topological solitons, characterised by the Hopf number. They serve as a fundamental prototype for three-dimensional magnetic quasiparticles and are an inspiration for novel device concepts in the field of spintronics. Based on a micromagnetic model and without considering temperature, the existence of such hopfions has been predicted in certain magnets with competing exchange interactions. However, physical realisation of freely moving hopfions in bulk magnets have so far been elusive. Here, we consider an effective Heisenberg model with competing exchange interactions and study the stability of small toroidal hopfions with Hopf number QH=1 by finding first-order saddle points on the energy surface representing the transition state for the decay of hopfions via the formation of two coupled Bloch points. We combine the geodesic nudged elastic band method and an adapted implementation of the dimer method to resolve the sharp energy profile of the reaction path near the saddle point. Our analysis reveals that the energy barrier can reach substantial height and is largely determined by the size of the hopfion relative to the lattice constant.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000955025000006
DO  - DOI:10.1103/PhysRevB.107.104404
UR  - https://juser.fz-juelich.de/record/1005287
ER  -