Aspect ratio dependence of magnetoresistivity in polycrystalline bismuth microwire arrays
Aspect ratio dependence of magnetoresistivity in polycrystalline bismuth microwire arrays
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DOI：
10.1063/1.2432876
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发表时间：
2007-02-01
影响因子：
3.2
通讯作者：
Nakamura, Hiroaki
中科院分区：
文献类型：
--
作者：
Hasegawa, Yasuhiro;Nakano, Hirofumi;Nakamura, Hiroaki
在0~2T的外加磁场和50~300K的温度下，对不同直径范围的多晶铋微线阵列和块体样品进行了磁阻测量。为了完全消除接触电阻，在微线阵列的端部沉积了一层薄膜。在整个测量温度范围内，测量的电阻率与多晶块状铋的电阻率非常一致，即使在电阻值不同的情况下也是如此。磁阻随外加磁场的增加而增大，不同长径比样品的磁阻随外加磁场的增加速率不同。有人推测，这种增长率的变化与纵横比有关。由于微丝阵列的长径比远大于大块样品的长径比，实验证实了块体铋对微丝阵列磁阻的抑制作用。微丝和纳米线阵列中的高深宽比对磁效应的几何贡献使得通过抑制磁阻和提高磁塞贝克系数来提高材料的热电性能成为可能。(C)2007年美国物理研究所。
Magnetoresistivity measurements of polycrystalline bismuth microwire arrays having a range of different diameters and a bulk sample were performed under applied magnetic fields between 0 and 2 T and temperatures from 50 to 300 K. A thin film layer was deposited on the terminations of the microwire arrays in order to completely eliminate contact resistance. The measured resistivities were in very good agreement with those of polycrystalline bulk bismuth over the entire measured temperature range, even when the resistances had different values. The magnetoresistivities increased when a magnetic field was applied, and the rate of increase of the magnetoresistivities with applied magnetic field varied in samples having different aspect ratios. It was conjectured that this variation in the rate of increase is related to the aspect ratio. Suppression of magnetoresistivity in the microwire arrays was confirmed experimentally using bulk bismuth since the aspect ratio of the microwire arrays was much larger than that of the bulk sample. The geometrical contribution of the high aspect ratio on the magnetic effect in microwire and nanowire arrays makes it possible to enhance the thermoelectric performance of materials by suppressing the magnetoresistivity and increasing the magneto-Seebeck coefficient. (c) 2007 American Institute of Physics.