Featureless quantum paramagnet with frustrated criticality and competing spiral magnetism on spin-1 honeycomb lattice magnet

Abstract

We study the spin-1 honeycomb lattice magnets with frustrated exchange interactions. The proposed microscopic spin model contains first-and second-neighbor Heisenberg interactions as well as the single-ion anisotropy. We establish a rich phase diagram that includes a featureless quantum paramagnet and various spin spiral states induced by the mechanism of order by quantum disorder. Although the quantum paramagnet is dubbed featureless, it is shown that the magnetic excitations develop a contour degeneracy in the reciprocal space at the band minima. These contour degenerate excitations are responsible for the frustrated criticality from the quantum paramagnet to the ordered phases. This work illustrates the effects of magnetic frustration on both magnetic orderings and the magnetic excitations. We discuss the experimental relevance to various Ni-based honeycomb lattice magnets.

Infinite critical boson non-Fermi liquid

“…Intuitively, the 2D counterpart of the present problem can be readily considered where a Fermi circle is coupled to a 1D critical boson contour. This critical boson contour can appear, for instance, on the interface of magnetic heterostructure 54 or in 2D-frustrated magnets 55 . Particular interest lies in the situation where the radius of the boson contour can be commensurate or incommensurate to the Fermi circle.…”

A helical superfluid in a frustrated honeycomb Bose-Hubbard model

“…The helical superfluid we explored thus maps directly on such a coplanar spin spiral state with the U(1) superfluid phase corresponding to the O(2) direction of the XY spin. Theoretical studies suggest the stability of such spiral states in a quantum easy-plane magnet [35] and in XY models (for spin-1/2, equivalent to the Bose-Hubbard model at half-filling in the U → ∞ hard-core limit, in contrast to the weak U limit considered here) with k 0 at high symmetry points selected by quantum fluctuations [72][73][74]. This contrasts with the corresponding Heisenberg O(3) model [26,28], which at nonzero temperature in 2d is always unstable (even with the usual linear dispersion) to a disordered state due to strongly coupled nonlinear spin wave fluctuations.…”

“…Another rich class of "codimension-one" frustrated systems [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], characterized by a bare dispersion that is nearly degenerate along d − 1 dimensions (d the spatial dimension), develop even in the bipartite lattice materials, frustrated by competing interactions. Examples include spinel materials such as MnSc 2 S 4 on 3d diamond lattice [26,27,30,39] and FeCl 3 on layered honeycomb lattice [40].…”

Infinite critical boson non-Fermi liquid

“…( 37) are evaluated separately under a low temperature approximation, /T 1, that sets up an upper limit for the frequency integral. Under the low temperature approximation, the function in the first term admits an expansion coth( /2T ) − 1 = 2f B ( ) 2T / , (38) where f B (x) is the boson distribution function. The first term is denoted as δ 1 (T ) and is calculated as,…”

“…This critical boson contour can appear for instance in 2D Rashba-type of DM interaction coupled magnets or in 2D frustrated magnets. 38,39 Particular interest lies in the situation where the radius of the boson ring is commensurate/incommensurate (C/IC) to the Fermi circle. 40 For the commensurate case, only finite Fermi points are connected by the boson contour.…”