New Fermionic Description of Quantum S = 1/2 Antiferromargnet

TL;DR

This paper introduces a new fermionic framework using Majorana fermions to describe S=1/2 antiferromagnets, enabling effective Hamiltonian derivation and revealing S=1 fermionic excitations in spin liquids.

Contribution

It proposes an irreducible Majorana fermion representation for S=1/2 spins, facilitating analysis of spin liquids without constraints.

Findings

Effective Hamiltonian for low-lying excitations derived

Excitations identified as S=1 real fermions

Representation simplifies analysis of strongly fluctuating antiferromagnets

Abstract

A novel approach to S =1/2 antiferromagnets with strong fluctuations based on the representation of spin-1/2 operators as bylinear forms of real (Majorana) fermions is suggested. This representation has the advantage of being irreducible without any constraints on the fermionic Hilbert space. This property allows to derive an effective Hamiltonian for low-lying excitations in the spin liquid state. It is proven that these excitations are S = 1 real fermions.