Semiclassical analysis of a magnetization plateau in a two-dimensional frustrated ferrimagnet

Abstract

We use a semiclassical large-S expansion to study a plateau at 1/3 saturation in the magnetization curve of a frustrated ferrimagnet on a spatially anisotropic kagomé lattice. The spins have both ferromagnetic and antiferromagnetic nearest-neighbor Heisenberg couplings, and a frustrating nextnearest-neighbor coupling in one lattice direction. The magnetization plateau appears at the classical level for a certain range of couplings, and quantum fluctuations significantly broaden it at both ends. Near the region of the phase diagram where the classical plateau destabilizes, we find an exotic "chiral liquid" phase that preserves translational and U (1) spin symmetry, in which bound pairs of magnons with opposite spins are condensed. We show how this state is obtained naturally from a relativistic field theory formulation. We comment on the relevance of the model to the material Cu3V2O7(OH) 2 · 2H2O (volborthite).

Frustrated two dimensional quantum magnets

“…28 merge into a point are very special. Analysis beyond the 1/S expansion suggests that around this point a finite region in J 1 /J 2 -h plane with an exotic phase exists, either with spin nematic order [125] or a chiral spin liquid phase [126].…”

Dynamics and Instabilities of the Shastry-Sutherland Model

“…Among them, the lowest one is a two-triplon state with k = (0, 0) and IREP B 1 , corresponding to vector chiral order [75][76][77]. Although their energies are slightly higher than the stripe magnetic instability within M ≤ 8, the situation may change in the M → ∞ limit, or if small perturbations are added to the original model.…”

“…While the tendency toward stripe ordering can be detected with inelastic NS, the experimental detection of the other phases is nontrivial. Lattice distortions induced by the order parameter through magnetostriction can provide indirect evidence if they are large enough to be detected [75][76][77]. Experimental knobs, such as pressure, doping, and magnetic field can drive the material into different instabilities [39,47].…”

Chiral liquid phase of simple quantum magnets

“…The experimental signatures of the VC order have been discussed in Refs. [18,30] They are related to the so-called "inverse Dzyaloshinskii-Moriya (DM)" effect, which was proposed as a mechanism for multi-ferroic behavior of spiral magnets [54][55][56]. Namely, a local VC order parameter S j × S l produces a net electric dipole proportional to e jl × S j × S l (where e jl ≡ (r j − r l )/|r j − r l |).…”

“…This singularity appears at second order in J z due to strong quantum renormalization of the interaction between magnons. Known from the previous renormalization group analysis, this spontaneous breaking of continuous U(1) and discrete Z 2 symmetries would become weakly first order, leading to a small but finite critical J z [17,18].The paper is organized as follows. In Sec.…”