Year: 2010
Type: article
Abstract: The minimal model to describe many spin-chain materials with ferroelectric properties is the Heisenberg model with ferromagnetic nearest-neighbor coupling ${J}_{1}$ and antiferromagnetic next-nearest-neighbor coupling ${J}_{2}$. Here we study the thermodynamics of this model using a density-matrix algorithm applied to transfer matrices. We find that the incommensurate spin-spin correlations---crucial for the ferroelectric properties and the analog of the classical spiral pitch angle---depend not only on the ratio ${J}_{2}/|{J}_{1}|$ but also strongly on temperature. We study small easy-plane anisotropies which can stabilize a vector chiral order as well as the finite-temperature signatures of multipolar phases, stable at finite magnetic field. Furthermore, we fit the susceptibilities of ${\text{LiCuVO}}_{4}$, ${\text{LiCu}}_{2}{\text{O}}_{2}$, and ${\text{Li}}_{2}{\text{ZrCuO}}_{4}$. Contrary to the literature, we find that for ${\text{LiCuVO}}_{4}$ the best fit is obtained with ${J}_{2}\ensuremath{\sim}90\text{ }\text{K}$ and ${J}_{2}/|{J}_{1}|\ensuremath{\sim}0.5$ and show that these values are consistent with the observed spin incommensurability. Finally, we discuss our findings concerning the incommensurate spin-spin correlations and multipolar orders in relation to future experiments on these compounds.
Source: Physical Review B
Author: J. Sirker
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2033537355