Abstract
Higher-order exchange interactions and quantum effects are widely known to play an important
role in describing the properties of low-dimensional magnetic compounds. Here we identify
the recently discovered two-dimensional (2D) van der Waals (vdW) CrI3 as a quantum
non-Heisenberg material with properties far beyond an Ising magnet as initially assumed.
We find that biquadratic exchange interactions are essential to quantitatively describe the
magnetism of CrI3 but requiring quantum rescaling corrections to reproduce its thermal
properties. The quantum nature of the heat bath represented by discrete electron-spin and
phonon-spin scattering processes induced the formation of spin fluctuations in the low temperature
regime. These fluctuations induce the formation of metastable magnetic domains
evolving into a single macroscopic magnetization or even a monodomain over surface areas
of a few micrometers. Such domains display hybrid characteristics of N´eel and Bloch types
with a narrow domain wall width in the range of 3-5 nm. Similar behaviour is expected for
the majority of 2D vdW magnets where higher-order exchange interactions are appreciable.
role in describing the properties of low-dimensional magnetic compounds. Here we identify
the recently discovered two-dimensional (2D) van der Waals (vdW) CrI3 as a quantum
non-Heisenberg material with properties far beyond an Ising magnet as initially assumed.
We find that biquadratic exchange interactions are essential to quantitatively describe the
magnetism of CrI3 but requiring quantum rescaling corrections to reproduce its thermal
properties. The quantum nature of the heat bath represented by discrete electron-spin and
phonon-spin scattering processes induced the formation of spin fluctuations in the low temperature
regime. These fluctuations induce the formation of metastable magnetic domains
evolving into a single macroscopic magnetization or even a monodomain over surface areas
of a few micrometers. Such domains display hybrid characteristics of N´eel and Bloch types
with a narrow domain wall width in the range of 3-5 nm. Similar behaviour is expected for
the majority of 2D vdW magnets where higher-order exchange interactions are appreciable.
| Original language | English |
|---|---|
| Journal | Advanced Materials |
| Publication status | Accepted/In press - 23 Oct 2020 |