磁梭结构中的机械诱导热击穿
Mechanically Induced Thermal Breakdown in Magnetic Shuttle Structures
摘要：
在电子输运的库仑阻塞机制下，提出了外磁场作用下磁性纳米机械器件中热致单电子“穿梭”不稳定性的理论.模型磁梭装置考虑包括一个可移动的金属颗粒悬浮在两个磁引线之间，这是保持在不同的温度和假设是完全自旋极化与反平行磁化。对于一个给定的温差穿梭被发现发生的外部磁场之间的一个较低的和一个较高的临界场强度，分离正常的小振幅“振动”制度的穿梭制度的区域。我们发现：（1）在高温极限下，上临界磁场饱和为一个常数，随着温度的降低，穿梭不稳定域扩大;（ii）较低的临界磁场不仅取决于模型中采用的与温度无关的唯象摩擦系数，而且还取决于内禀摩擦（其在高温极限下消失）由磁交换力和量子点与引线之间的电子隧穿引起。讨论了利用热驱动磁梭系统采集热击穿现象的可行性。
英文摘要：
A theory of a thermally induced single-electron "shuttling" instability in a magnetic nanomechanical device subject to an external magnetic field is presented in the Coulomb blockade regime of electron transport. The model magnetic shuttle device considered comprises a movable metallic grain suspended between two magnetic leads, which are kept at different temperatures and assumed to be fully spin polarized with antiparallel magnetizations. For a given temperature difference shuttling is found to occur for a region of external magnetic fields between a lower and an upper critical field strength, which separate the shuttling regime from normal small-amplitude "vibronic" regimes. We find that (i) the upper critical magnetic field saturates to a constant value in the high temperature limit and that the shuttle instability domain expands with a decrease of the temperature, (ii) the lower critical magnetic field depends not only on the temperature independent phenomenological friction coefficient used in the model but also on intrinsic friction (which vanishes in the high temperature limit) caused by magnetic exchange forces and electron tunneling between the quantum dot and the leads. The feasibility of using thermally driven magnetic shuttle systems to harvest thermal breakdown phenomena is discussed.
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