6 research outputs found
Jammed spin liquid in the bond-disordered kagome Heisenberg antiferromagnet
We study a class of continuous spin models with bond disorder including the kagome Heisenberg antiferromagnet. For weak disorder strength, we find discrete ground states whose number grows exponentially with system size. These states do not exhibit zero-energy excitations characteristic of highly frustrated magnets but instead are local minima of the energy landscape. This represents a spin liquid version of the phenomenon of jamming familiar from granular media and structural glasses. Correlations of this jammed spin liquid, which upon increasing the disorder strength gives way to a conventional spin glass, may be algebraic (Coulomb-type) or exponential.Physic
Dynamics and energy landscape of the jammed spin-liquid
We study the low temperature static and dynamical properties of the classical bond-disordered antiferromagnetic Heisenberg model on the kagome lattice. This model has recently been shown to host a new type of spin liquid exhibiting an exponentially large number of discrete ground states. Surprisingly, despite the rigidity of the groundstates, we establish the vanishing of the corresponding spin stiffness. Locally, the low-lying eigenvectors of the Hessian appear to exhibit a fractal inverse participation ratio. Its spin dynamics resembles that of Coulomb Heisenberg spin liquids, but exhibits a new low-temperature dynamically arrested regime, which however gets squeezed out with increasing system size. We also probe the properties of the energy landscape underpinning this behaviour, and find energy barriers between distinct ground states vanishing with system size. In turn the local minima appear highly connected and the system tends to lose memory of its inital state in an accumulation of soft directions.Physic
Field-induced States and Excitations in the Quasicritical Spin-1/2 Chain Linarite
The mineral linarite, PbCuSO(OH), is a spin 1/2 chain with
frustrating nearest neighbor ferromagnetic and next-nearest neighbor
antiferromagnetic exchange interactions. Our inelastic neutron scattering
experiments performed above the saturation field establish that the ratio
between these exchanges is such that linarite is extremely close to the quantum
critical point between spin-multipolar phases and the ferromagnetic state.
However, the measured complex magnetic phase diagram depends strongly on the
magnetic field direction. The field-dependent phase sequence is explained by
our classical simulations of a nearly critical model with tiny orthorhombic
exchange anisotropy. The simulations also capture qualitatively the measured
variations of the wave vector as well as the staggered and the uniform
magnetizations in an applied field
High-Angular Momentum Excitations in Collinear Antiferromagnet FePS<sub>3</sub>
We report on magneto-optical studies of the quasi-two-dimensional
van der Waals antiferromagnet FePS3. Our measurements reveal
an excitation that closely resembles the antiferromagnetic resonance
mode typical of easy-axis antiferromagnets; nevertheless, it displays
an unusual, four-times larger Zeeman splitting in an applied magnetic
field. We identify this excitation with an |Sz| = 4 multipolar magnona single-ion
4-magnon bound statethat corresponds to a full reversal of
a single magnetic moment of the Fe2+ ion. We argue that
condensation of multipolar magnons in large-spin materials with a
strong magnetic anisotropy can produce new exotic states