Unraveling the role of the magnetic anisotropy on thermoelectric response: a theoretical and experimental approach
M. A. Correa, M. Gamino, A. S. de Melo, M. V. P. Lopes, J. G. S. Santos, A. L. R. Souza, S. A. N. França Junior, A. Ferreira, S. Lanceros-Méndez, F. Vaz, F. Bohn
Magnetic anisotropies have key role to taylor magnetic behavior in ferromagnetic systems. Further, they are also essential elements to manipulate the thermoelectric response in Anomalous Nernst (ANE) and Longitudinal Spin Seebeck systems (LSSE). We propose here a theoretical approach and explore the role of magnetic anisotropies on the magnetization and thermoelectric response of noninteracting multidomain ferromagnetic systems. The magnetic behavior and the thermoelectric curves are calculated from a modified Stoner Wohlfarth model for an isotropic system, a uniaxial magnetic one, as well as for a system having a mixture of uniaxial and cubic magnetocrystalline magnetic anisotropies. It is verified remarkable modifications of the magnetic behavior with the anisotropy and it is shown that the thermoelectric response is strongly affected by these changes. Further, the fingerprints of the energy contributions to the thermoelectric response are disclosed. To test the robustness of our theoretical approach, we engineer films having the specific magnetic properties and compare directly experimental data with theoretical results. Thus, experimental evidence is provided to confirm the validity of our theoretical approach. The results go beyond the traditional reports focusing on magnetically saturated films and show how the thermoelectric effect behaves during the whole magnetization curve. Our findings reveal a promising way to explore the ANE and LSSE effects as a powerful tool to study magnetic anisotropies, as well as to employ systems with magnetic anisotropy as sensing or elements in technological applications.
Giant thermoelectric power factor anisotropy in PtSb$_{1.4}$Sn$_{0.6}$
我们报道了白铁矿结构型PtSb $_{1.4}$ Sn $_{0.6}$的热电功率因子（$S^2σ$）的巨大各向异性。PtSb $_{1.4}$ Sn $_{0.6}$是一种新相，它不同于PtSb $_2$和PtSn $_2$，后者分别以立方$Pa\bar{3}$黄铁矿和$Fm\bar{3}m$萤石晶胞对称性结晶。热流沿正交单胞不同主方向作用的$S^2σ$的巨大差异主要源于各向异性的Seebeck系数。
Anisotropic thermoelectric properties of EuCd$_{2}$As$_{2}$ : An Ab-initio study
为了寻找更好的热电材料，我们采用\textit{ab-initio}密度泛函理论和半经典Boltzmann输运理论在常数弛豫时间近似下系统地研究了122 Zintl相化合物EuCd $_{2}$ As $_{2}$的热电性质.考虑到基态磁性结构为A型反铁磁（A-AFM）和非磁性（NM）结构，我们计算了Seebeck系数、电导率和热导率、功率因数和品质因数（ZT）等热电参数随温度和化学势的变化。几乎所有的热电参数都显示出$xx$和$zz$方向之间的各向异性，这在A-AFM的情况下比在NM中更强。当空穴掺杂时，化合物的A-AFM相和NM相都显示出更好的热电性能。在A-AFM相中，沿$zz$方向观察到高的Seebeck系数和低的电子热导率。在500 K时，A-AFM相的ZT为1.79，NM相的ZT为$\sim$ 1，这表明EuCd $_{2}$ As $_{2}$在p掺杂时是可行的热电材料。
Anisotropic Phonon Heat Flow and Thermoelectric Response in Tetragonal GeS$_2$ and GeSe$_2$
IIS (Deemed to be University), Jaipur, Rajasthan 302020, India（印度拉贾斯坦邦斋浦尔 IIS（视为大学））；Mody University of Science and Technology, Lakshmangarh, Sikar, Rajasthan 332311, India（印度拉贾斯坦邦西卡尔拉克什曼加尔莫迪科学与技术大学）
