The spin-Seebeck effect (SSE) has long been considered as an effective route to generate pure spin currents by using a temperature gradient in magnetic materials. By substituting some boron or nitrogen atoms with carbon atoms in boron–nitrogen nanotubes (BNNTs), we constructed some magnetic BNNT heterojunctions, and found that spin-dependent currents with opposite flow directions can be driven through the heterojunction by using a temperature gradient, supporting that a promising SSE occurs in these nanotube-based devices. The spin polarization of the thermal spin-dependent currents is up to 70% at room temperature, and the rotational symmetry of carbon substitutions in the central scattering region influences the thermal charge and spin currents significantly. A negative differential resistance effect induced by the competition between the temperature gradient and the spin thermopower is also uncovered. Besides, spin-filtering and spin-dependent diode effects induced by a bias voltage are also observed in the BNNT heterojunctions. These theoretical results give us deep understanding of how spin currents are driven in magnetic nanotube-based heterojunctions, and provide us with a feasible route to design spin caloritronic devices based on nanotube structures.

中文翻译：

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硼-氮纳米管异质结中自旋依赖性塞贝克效应，自旋滤波和二极管效应

长期以来，自旋塞贝克效应（SSE）被认为是通过利用磁性材料中的温度梯度来产生纯自旋电流的有效途径。通过用硼氮氮纳米管（BNNT）中的碳原子取代一些硼或氮原子，我们构造了一些磁性BNNT异质结，并发现可以通过使用温度梯度驱动具有相反流向的自旋相关电流通过异质结，在这些基于纳米管的设备中发生了有希望的SSE。在室温下，热自旋相关电流的自旋极化高达70％，并且中心散射区中碳置换的旋转对称性显着影响热电荷和自旋电流。还没有发现由温度梯度和自旋热功率之间的竞争引起的负差分电阻效应。此外，在BNNT异质结中还观察到由偏置电压引起的自旋滤波和自旋相关的二极管效应。这些理论结果使我们对基于磁性纳米管的异质结中如何驱动自旋电流有深刻的了解，并为我们提供了一种基于纳米管结构设计自旋热电子器件的可行途径。