Magnetic field dependent thermal conductance in La0.67Ca0.33MnO3
Magnetic field dependent thermal conductance in La0.67Ca0.33MnO3
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DOI：
10.1016/j.jmmm.2014.12.083
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发表时间：
2015-05-01
影响因子：
2.7
通讯作者：
Jakob, G.
中科院分区：
文献类型：
--
作者：
Euler, C.;Holuj, P.;Jakob, G.
采用差分3 Ω技术测量了异质外延薄膜La_（0.67）Ca_（0.33）MnO_3（LCMO）的低温离面热导。的热导率的磁场依赖性达到高达23%的值。观察到的效果是最大的附近的金属-绝缘体过渡，因为在热导的增强是由庞磁阻效应增加电子的贡献的热导触发。通过在氧气气氛中对样品进行后退火来调节最大变化的点。样品具有较高的转变温度和较低的外延应变显示出较低的磁场依赖性高达8%的零场值。低应变状态下的样品似乎符合Wiedemann-Franz定律，而高应变状态下的样品则不符合。拉曼光谱被用来解释这种差异，即由晶胞的旋转畸变引起的声子态密度增强。我们的结果表明，在系统中具有强的电子晶格相互作用的声子谱操纵是可能的磁场。(C)© 2015 Elsevier B. V.版权所有
Using the differential 3 omega technique we measured the low-temperature out-of-plane thermal conductance of heteroepitaxial thin film La0.67Ca0.33MnO3 (LCMO). The magnetic field dependence of the thermal conductance reached values of up to 23%. The effect was observed to be largest in the vicinity of the metal-insulator transition, since the enhancement in thermal conductance is triggered by the colossal magnetoresistance effect increasing the electronic contribution to the thermal conductance. The point of the maximal change was adjusted by post-annealing the samples in an oxygen atmosphere. Samples with a higher transition temperature and lower epitaxial strain displayed a lower magnetic field dependence of up to 8% of the zero-field value. While the samples with a low strain state seemingly obeyed the Wiedemann-Franz law, those under high strain did not Raman spectroscopy was applied to explain this discrepancy by an enhanced phononic density of states caused by rotational distortions of the unit cell. Our results show that in systems with strong electron-lattice interaction manipulation of the phonon spectrum is possible by magnetic fields. (C) 2015 Elsevier B.V. All rights reserved