Spin supersolid phase in coupled alternating spin chains

F Heydarinasab,J Abouie

doi:10.1038/s41598-018-26169-y

Abstract

We study the ground state phase diagram of a two dimensional mixed-spin system of coupled alternating spin-1 and 1/2 chains with a stripe supersolid phase. Utilizing different analytical and numerical approaches such as mean field approximation, cluster mean field theory and linear spin wave theory, we demonstrate that our system displays a rich ground state phase diagram including novel stripe supersolid, solids with different fillings and super-counterfluid phases, in addition to a stripe solid with half filling, superfluid and Mott insulating phases. In order to find a minimal mixed-spin model for stripe supersolidity, in the second part of the paper we consider two kinds of mixed-spin system of coupled alternating spin-1 and 1/2 chains with (i) anisotropic nearest neighbor interactions, (ii) anisotropic hoppings and study their ground state phase diagrams. We demonstrate that, for the systems with uniform hoppings, the repulsive intra-chains interactions are necessary for stripe supersolidity. In this case the minimal two dimensional mixed-spin model is a system of spin-1 and spin-1/2 XXZ chains, interacting via Ising Hamiltonian. In the case of anisotropic hoppings, a system of coupled Ising chains is the minimal model.

Highlights

Utilizing different analytical and numerical approaches such as mean field approximation, cluster mean field theory and linear spin wave theory, we demonstrate that our system displays a rich ground state phase diagram including novel stripe supersolid, solids with different fillings and super-counterfluid phases, in addition to a stripe solid with half filling, superfluid and Mott insulating phases
By obtaining the cluster mean field theory (CMFT) ground state phase diagrams of these systems, we demonstrate that the appearance of the STS order strongly depends on the amounts of intra-chains NN interaction
In the absence of intra-chains interaction, at V1 = 0, each 1D lattices are described by a XY Hamiltonian and no supersolid order appears in the ground state phase diagram of the system

Summary

OPEN Spin supersolid phase in coupled alternating spin chains

We study the ground state phase diagram of a two dimensional mixed-spin system of coupled alternating spin-1 and 1/2 chains with a stripe supersolid phase. In order to find a minimal mixedspin model for stripe supersolidity, in the second part of the paper we consider two kinds of mixed-spin system of coupled alternating spin-1 and 1/2 chains with (i) anisotropic nearest neighbor interactions, (ii) anisotropic hoppings and study their ground state phase diagrams. We investigate the ground state phase diagram of the CAS model using different analytical and numerical approaches such as mean field (MF) approximation, cluster mean field theory (CMFT) and linear spin wave theory (LSWT).

Our Model

Ground State Phase Diagram

Anisotropic CAS Models

Methods

Summary and Conclusion

Additional Information