A mean field theory for the spin ladder system

TL;DR

This paper introduces a mean field theory for spin ladder systems using Jordan-Wigner transformation, accurately predicting energy gaps and excitation spectra that align with experimental and numerical data.

Contribution

It presents a novel mean field approach for spin ladders that effectively captures the energy gap and excitation spectra, validated against experiments and simulations.

Findings

Even-leg ladders have an energy gap close to experimental values.

Odd-leg ladders are gapless at low energies.

Calculated spectra agree with experimental and numerical results.

Abstract

In the present paper, we propose a mean field approach for spin ladders based upon the Jordan-Wigner transformation along an elaborately ordered path. We show on the mean field level that ladders with even number legs open a energy gap in their low energy excitation with a magnitude close to the corresponding experimental values, whereas the low energy excitation of the odd-number-leg ladders are gapless. It supports the validity of our approach. We then calculate the gap size and the excitation spectra of 2-leg-ladder system. Our result is in good agreement with both the experimental data and the numerical results.