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arXiv 0909.4579cond-mat.str-el
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多铁性自旋链的热力学

Thermodynamics of multiferroic spin chains

J. Sirker

摘要:

描述许多具有铁电性质的自旋链材料的极小模型是具有铁磁近邻耦合J1和反铁磁次近邻耦合J2的海森堡模型。在这里,我们研究这个模型的热力学使用的密度矩阵算法应用到传递矩阵。我们发现,不相称的自旋-自旋相关-铁电性能和经典螺旋螺距角的模拟至关重要-不仅依赖于比J2/ |J1|,但也强烈地依赖于温度。我们研究了小的易平面各向异性,它可以稳定的矢量手征顺序,以及多极相的有限温度签名,稳定在有限的磁场。此外,我们还拟合了LiCuVO 4、LiCu 2 O2和Li 2 ZrCuO 4的磁化率。与文献相反,我们发现,对于LiCuVO 4的最佳拟合是在J2 ~ 90 K和J2/ |J1| ~ 0.5时获得的,并且表明这些值与观察到的自旋不可逆性是一致的。最后,我们讨论了我们的研究结果有关的不相称的自旋自旋相关性和多极秩序在未来的实验对这些化合物。

英文摘要:

The minimal model to describe many spin chain materials with ferroelectric properties is the Heisenberg model with ferromagnetic nearest neighbor coupling J1 and antiferromagnetic next-nearest neighbor coupling J2. 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 analogue of the classical spiral pitch angle - depend not only on the ratio J2/|J1| 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 LiCuVO4, LiCu2O2, and Li2ZrCuO4. Contrary to the literature, we find that for LiCuVO4 the best fit is obtained with J2 ~ 90 K and J2/|J1| ~ 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.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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