SciPost Phys. Core 3, 004 (2020) ·
published 4 September 2020

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We study the rareearth magnets on a honeycomb lattice, and are particularly interested in the experimental consequences of the highly anisotropic spin interaction due to the spinorbit entanglement. We perform a hightemperature series expansion using a generic nearestneighbor Hamiltonian with anisotropic interactions, and obtain the heat capacity, the parallel and perpendicular spin susceptibilities, and the magnetic torque coefficients. We further examine the electron spin resonance linewidth as an important signature of the anisotropic spin interactions. Due to the small interaction energy scale of the rareearth moments, it is experimentally feasible to realize the strongfield regime. Therefore, we perform the spinwave analysis and study the possibility of topological magnons when a strong field is applied to the system. The application and relevance to the rareearth Kitaev materials are discussed.
SciPost Phys. Core 3, 003 (2020) ·
published 20 August 2020

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We study quantum dynamics on noncommutative spaces of negative curvature,
focusing on the hyperbolic plane with spatial noncommutativity in the presence
of a constant magnetic field. We show that the synergy of noncommutativity and
the magnetic field tames the exponential divergence of operator growth caused
by the negative curvature of the hyperbolic space. Their combined effect
results in a firstorder transition at a critical value of the magnetic field
in which strong quantum effects subdue the exponential divergence for {\it all}
energies, in stark contrast to the commutative case, where for high enough
energies operator growth always diverge exponentially. This transition
manifests in the entanglement entropy between the `left' and `right' Hilbert
spaces of spatial degrees of freedom. In particular, the entanglement entropy
in the lowest Landau level vanishes beyond the critical point. We further
present a nonlinear solvable bosonic model that realizes the underlying
algebraic structure of the noncommutative hyperbolic plane with a magnetic
field.
SciPost Phys. Core 3, 002 (2020) ·
published 31 July 2020

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We study the limit of Dseries minimal models when the central charge tends
to a generic irrational value $c\in (\infty, 1)$. We find that the limit
theory's diagonal threepoint structure constant differs from that of Liouville
theory by a distribution factor, which is given by a divergent Verlinde
formula. Nevertheless, correlation functions that involve both nondiagonal and
diagonal fields are smooth functions of the diagonal fields' conformal
dimensions. The limit theory is a nontrivial example of a nondiagonal,
nonrational, solved twodimensional conformal field theory.
Sergio Enrique Tapias Arze, Pieter W. Claeys, Isaac Pérez Castillo, JeanSébastien Caux
SciPost Phys. Core 3, 001 (2020) ·
published 22 July 2020

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We consider the dynamics of an XY spin chain subjected to an external transverse field which is periodically quenched between two values. By deriving an exact expression of the Floquet Hamiltonian for this outofequilibrium protocol with arbitrary driving frequencies, we show how, after an unfolding of the Floquet spectrum, the parameter space of the system is characterized by alternations between local and nonlocal regions, corresponding respectively to the absence and presence of Floquet resonances. The boundary lines between regions are obtained analytically from avoided crossings in the Floquet quasienergies and are observable as phase transitions in the synchronized state. The transient behaviour of dynamical averages of local observables similarly undergoes a transition, showing either a rapid convergence towards the synchronized state in the local regime, or a rather slow one exhibiting persistent oscillations in the nonlocal regime, where explicit decay coefficients are presented.