To study the effects of paramagnetic spins on phonons, both the in-plane and the c-axis heat transport of GdBaCo_{2}O_{5+x} (GBCO) single crystals are measured at low temperature down to 0.36 K and in magnetic field up to 16 T. It is found that the phonon heat transport is very strongly affected by the magnetic field and nearly 5 times increase of the thermal conductivity in several Tesla field is observed at 0.36 K. It appears that phonons are resonantly scattered by paramagnetic spins in zero field and the application of magnetic field removes such strong scattering, but the detailed mechanism is to be elucidated.
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。
