Magnon-drag thermopower in antiferromagnets versus ferromagnets
Magnon-drag thermopower in antiferromagnets versus ferromagnets
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DOI：
10.1039/c9tc06330g
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发表时间：
2020-03-28
影响因子：
6.4
通讯作者：
Vashaee, Daryoosh
中科院分区：
文献类型：
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作者：
Polash, Md. Mobarak Hossain;Mohaddes, Farzad;Vashaee, Daryoosh
磁振子电子阻力(MED)向顺磁领域的扩展最近表明，它可以产生比经典扩散热电势更大的热电势，从而导致热电优值系数大于1。由于其不同的性质，铁磁(FM)和反铁磁(AFM)磁子与载流子的相互作用不同，产生的阻力热电势也不同。问题是，在调频半导体和原子力显微镜半导体中，MED哪个更强？详细研究了两种材料体系，即MnSb和CrSb，它们在许多方面都很相似，但前者是FM，后者是AFM，并对它们的MED性能进行了比较。与FM相比，AFM的三个特征，即磁振子模的双简并、更高的磁振子群速度和更长的磁振子弛豫时间，可以导致一阶MED热电势的增强。一种效应，磁非电子弛豫，导致原子力显微镜中更高的二阶效应，从而降低了MED热电势。然而，人们普遍认为，在原子力显微镜中，一阶效应占主导地位，并导致更高的阻力热电势，如本案例研究所见。
The extension of magnon electron drag (MED) to the paramagnetic domain has recently shown that it can create a thermopower more significant than the classical diffusion thermopower resulting in a thermoelectric figure-of-merit greater than unity. Due to their distinct nature, ferromagnetic (FM) and antiferromagnetic (AFM) magnons interact differently with the carriers and generate different amounts of drag-thermopower. The question arises of whether the MED is stronger in FM or in AFM semiconductors. Two material systems, namely MnSb and CrSb, which are similar in many aspects except that the former is FM and the latter AFM, were studied in detail, and their MED properties were compared. Three features of AFMs compared to FMs, namely double degeneracy of the magnon modes, higher magnon group velocity, and longer magnon relaxation time, can lead to enhanced first-order MED thermopower. One effect, magnon-electron relaxation, leads to a higher second-order effect in AFMs that reduces the MED thermopower. However, it is generally expected that the first-order effect dominates and leads to a higher drag thermopower in AFMs, as seen in this case study.