Thermally-induced mimicry of quantum cluster excitations and implications for the magnetic transition in FePSe${}_3$

Abstract

In two dimensional magnets, the interplay of thermal fluctuations and spin anisotropy control the existence of long-range magnetic order. In the van der Waals antiferromagnets FePX${}_3$, orbital degeneracy in the $t2g$ levels of the Fe${}^{2+}$ ions in octahedral coordination yields strong uniaxial anisotropy, which stabilizes magnetic order up to T$\approx$100 K. Recent inelastic neutron scattering measurements around the magnetic ordering transition have shown the existence of a broad spectrum of magnetic fluctuations with nontrivial momentum dependence, which has been interpreted as evidence for localized entangled cluster excitations. In this paper, we offer an alternative interpretation using classical nonlinear spin dynamics simulations. We present stochastic Landau Lifshitz dynamics simulations that reproduce the neutron scattering measurements of Chen et al. [npj Quantum Mater. 9, 40 (2024)] on FePSe${}_3$. These calculations faithfully explain the dynamical structure factor's momentum and energy dependence and point to a classical origin for the excitations observed in neutron spectroscopy and that the order-disorder transition can be understood in terms of thermal fluctuations overcoming the anisotropy energy.

11 pages, 4 figures. Published in Physical Review B

References in corpus (26)

• Magnetic 2D materials and heterostructures
• Suppression of magnetic ordering in XXZ-type antiferromagnetic monolayer NiPS3
• Evolution of interlayer and intralayer magnetism in three atomically thin chromium trihalides
• Spontaneous Magnon Decays
• Dirac magnons in honeycomb ferromagnets
• On the Remarkable Superconductivity of FeSe and its Close Cousins
• The magnetic properties and structure of the quasi-two-dimensional antiferromagnet CoPS${}_3$
• Magnetic anisotropy and exchange interactions of two-dimensional FePS${}_3$, NiPS${}_3$ and MnPS${}_3$ from first principles calculations
• Controlling magnetic exchange and anisotropy by non-magnetic ligand substitution in layered MPX3 (M = Ni, Mn; X = S, Se)
• Biquadratic and ring exchange interactions in orthorhombic perovskite manganites
• Molecular spin resonance in the geometrically frustrated MgCr2O4 magnet by inelastic neutron scattering
• Excitations in the ordered and paramagnetic states of honeycomb magnet Na2Co2TeO6
• The magnetic dynamics of NiPS${}_3$
• Classical spin dynamics based on SU($N$) coherent states
• Geometric integration of classical spin dynamics via a mean-field Schrödinger equation
• Spin wave Hamiltonian and anomalous scattering in NiPS${}_3$
• Langevin dynamics of generalized spins as SU($N$) coherent states
• Evidence for biquadratic exchange in the quasi-two-dimensional antiferromagnet FePS${}_3$
• Antiferromagnetism in two-dimensional materials: progress and computational challenges
• Observation of elastic anomalies driven by coexisting dynamical spin Jahn-Teller effect and dynamical molecular spin state in paramagnetic phase of the frustrated MgCr${}_2$O${}_4$$
• Spin wave spectra of single crystal CoPS${}_3$
• Nano-scale collinear multi-Q states driven by higher-order interactions
• Quantum and classical spin dynamics across temperature scales in the S = 1/2 Heisenberg antiferromagnet
• Diffusive Excitonic Bands from Frustrated Triangular Sublattice in a Singlet-Ground-State System
• Floating Phase in 2D ANNNI Model
• Quadrupole moments and their interactions in the triangular lattice antiferromagnet FeI${}_2$

Cited by in corpus (1)

• Signatures of three-state Potts nematicity in spin excitations of the van der Waals antiferromagnet FePSe${}_3$