We study the low-temperature heat transport of HoMnO_3 single crystals to probe the magnetic structures and their transitions induced by magnetic field. It is found that the low-T thermal conductivity (κ) shows very strong magnetic-field dependence, with the strongest suppression of nearly 90% and the biggest increase of 20 times of κcompared to its zero-field value. In particular, some ``dip"-like features show up in κ(H) isotherms for field along both the ab plane and the c axis. These behaviors are found to shed new light on the complex H-T phase diagram and the field-induced re-orientations of Mn^{3+} and Ho^{3+} spin structures. The results also demonstrate a significant spin-phonon coupling in this multiferroic compound.
本文研究了自旋为1/2的低交换耦合梯形结构（$J\llΘ_D$）在强磁场$B$作用下的磁热导率理论模型。我们的热输运理论考虑了一维晶格中自旋子与晶格声子模耦合的贡献。本文采用阶梯哈密顿量到XXZ自旋链上的一个较弱有效场的映射B_{eff} = B-B_{0} $, where $ B_{0} =（B_{c1} + B_{c2}）/2 $ corresponds to half-filling of the spinon band. This provides a low-energy theory for the spinon excitations and their coupling to the phonons. The coupling of acoustic longitudinal phonons to spinons gives rise to hybridization of spinons and phonons, and provides an enhanced $ B $-dependant scattering of phonons on spinons. Using a memory matrix approach, we show that the interplay between several scattering mechanisms, name…
Anisotropic phonon conduction and lattice distortions in CMR-type bilayer manganite (La$_{1-z}$Pr$_{z}$)$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$ (z=0,0.2,0.4 and 0.6) single crystals
本文系统地研究了（La $_{1-z}$ Pr $_{z}$）$_{1.2}$ Sr $_{1.8}$ Mn $_{2}$ O $_{7}$（$z$（Pr）= 0.2，0.4）单晶的热导率随温度和磁场的变化。和0.6。晶格畸变由于Pr-取代和各向异性的热导率在双层锰氧化物中的不同的弛豫模型的基础上提出的金属和绝缘状态的局部晶格畸变的Maderda等。巨磁热效应的缩放作为磁化强度的函数，并讨论了由于Pr-取代的$e_g$ -电子轨道状态的占领的系统变化的基础上。
