Original Article

Subject Category: Electronic, magnetic and superconducting materials

Citation: NPG Asia Materials (2014) 6, e127; doi:10.1038/am.2014.74
Published online 19 September 2014

Efficient thermal spin injection using CoFeAl nanowire
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Shaojie Hu1, Hiroyoshi Itoh2,3 and Takashi Kimura3,4

  1. 1Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka, Japan
  2. 2Department of Pure and Applied Physics, Kansai University, Suita, Japan
  3. 3CREST, Japan Science and Technology Agency, Tokyo, Japan
  4. 4Department of Physics, Kyushu University, Fukuoka, Japan

Correspondence: Professor T Kimura, Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan. E-mail: t-kimu@phys.kyushu-u.ac.jp

Received 28 February 2014; Revised 20 July 2014; Accepted 22 July 2014

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Abstract

Nanoelectronic devices based on electron spin can overcome the physical limitations of the present semiconductor technology because of their low power consumption while exploiting the spin degree of freedom of electrons. Although enhancing the efficiency of generation of the spin current is imperative and a primary issue for the practical application of spin-based electronics, seamless device integration with the conventional complementary metal-oxide semiconductor technology is another important milestone for developing spin-based nanoelectronics. In particular, the preparation of nanosized, magnetic, multilayered structures with electrical connections to individual complementary metal-oxide semiconductor circuits significantly complicates the fabrication procedure of nanoelectronic devices. Thermal spin injection, which is a recently discovered unique characteristic of spin current, may be an innovative method for simplifying device integration without the need for electricity, namely wireless spintronics. However, the feasibility of using the thermal spin injection method is poor because of its extremely low-generation efficiency. Here, we demonstrate that a highly spin-polarized, ferromagnetic CoFeAl electrode with a favorable band structure has excellent properties for thermal spin injection. The spin-dependent Seebeck coefficient is approximately 70μVK−1, which facilitates highly efficient generation of the spin current from heat. The heat generates approximately 100 times more spin voltage than a conventional ferromagnetic injector at room temperature. This innovative demonstration may open a new route for spin-device integration and its applications.

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