26 research outputs found
Magnetic vortex crystals in frustrated Mott insulator
Quantum fluctuations become particularly relevant in highly frustrated
quantum magnets and can lead to new states of matter. We provide a simple and
robust scenario for inducing magnetic vortex crystals in frustrated Mott
insulators. By considering a quantum paramagnet that has a gapped spectrum with
six-fold degenerate low energy modes, we study the magnetic field induced
condensation of these modes. We use a dilute gas approximation to demonstrate
that a plethora of multi- condensates are stabilized for different
combinations of exchange interactions. This rich quantum phase diagram includes
magnetic vortex crystals, which are further stabilized by symmetric exchange
anisotropies. Because magnetic skyrmion and domain wall crystals have already
been predicted and experimentally observed, this novel vortex phase completes
the picture of emergent crystals of topologically nontrivial spin
configurations.Comment: 12 pages, 12 figures; published in Phys. Rev.
Crossover Behavior from Decoupled Criticality
We study the thermodynamic phase transition of a spin Hamiltonian comprising
two 3D magnetic sublattices. Each sublattice contains XY spins coupled by the
usual bilinear exchange, while spins in different sublattices only interact via
biquadratic exchange. This Hamiltonian is an effective model for XY magnets on
certain frustrated lattices such as body centered tetragonal. By performing a
cluster Monte Carlo simulation, we investigate the crossover from the 3D-XY
fixed point (decoupled sublattices) and find a systematic flow toward a
first-order transition without a separatrix or a new fixed point. This strongly
suggests that the correct asymptotic behavior is a first-order transition.Comment: 10 pages, 3 figures; added reference