摘要
Magnetism in recently discovered van der Waals materials has opened several avenues in the study of fundamental spin interactions in truly two-dimensions.A paramount question is what effect higher-order interactions beyond bilinear Heisenberg exchange have on the magnetic properties of few-atom thick compounds.Here we demonstrate that biquadratic exchange interactions,which is the simplest and most natural form of non-Heisenberg coupling,assume a key role in the magnetic properties of layered magnets.Using a combination of nonperturbative analytical techniques,non-collinear first-principles methods and classical Monte Carlo calculations that incorporate higher-order exchange,we show that several quantities including magnetic anisotropies,spin-wave gaps and topological spin-excitations are intrinsically renormalized leading to further thermal stability of the layers.
基金
EJGS acknowledges computational resources through the UK Materials and Molecular Modelling Hub for access to THOMAS supercluster,which is partially funded by EPSRC(EP/P020194/1)
CIRRUS Tier-2 HPC Service(ec131 Cirrus Project)at http://www.cirrus.ac.uk EPCC funded by the University of Edinburgh and EPSRC(EP/P020267/1)
ARCHER UK National Supercomputing Service(http://www.archer.ac.uk)via Project d429
EJGS acknowledges the EPSRC Early Career Fellowship(EP/T021578/1)
the University of Edinburgh for funding support.
