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arXiv · 2606.28521

Mixed-spin Heisenberg ladders in a magnetic field

D. S. Almeida·A. S. Bibiano·W. M. da Silva·R. R. Montenegro-Filho
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Abstract

In this work, we study alternating mixed-spin $(s,S)$ Heisenberg ladders in the magnetic field $h$ using density matrix renormalization group and linear spin-wave calculations. The $h$ \textit{versus} interchain coupling $J_\perp$ phase diagram for the $(1/2,1)$ case is investigated in detail. { In particular, we demonstrate the compatibility between the critical line estimates and magnetic ordering by analyzing chains with variable values of $J_\perp$ and of $h$ along the chain, $J_\perp$ and $h$ scans, and considering the usual case of chains with uniform couplings}. The magnetization plateau at 1/3 of saturation magnetization, 1/3 - plateau, is observed for $J_\perp>0$ and in a limited range for $J_\perp<0$. The critical Kosterlitz-Thouless transition point, where the 1/3 - plateau closes, is identified through a finite-size analysis of the transverse spin correlation functions.

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D. S. Almeida, A. S. Bibiano, W. M. da Silva, R. R. Montenegro-Filho. 2026-06-26. Mixed-spin Heisenberg ladders in a magnetic field. https://doi.org/10.1103/physreve.111.014149

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