Room-temperature generation of giant pure spin currents using epitaxial Co2FeSi spin injectors

Kimura, Takashi; Hashimoto, Naoki; Yamada, Shinya; Miyao, Masanobu; Hamaya, Kohei

doi:10.1038/am.2012.16

Cited by 107 publications

(122 citation statements)

References 28 publications

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“…Thus, the strong enhancement of the spin signal by a factor of 10 is attributed to the efficient generation and detection of the spin current because CFA has a large spin polarization and the spin current backflow is significantly reduced. 26 The obtained spin polarization of the present CFA is close to the previously reported values, although the Al content and electrical resistivity are notably different, 19,20 which suggests that our CFA has a different crystal structure from those in the previous reports.…”

Section: Resultssupporting

confidence: 75%

Efficient thermal spin injection using CoFeAl nanowire

Itoh

Kimura

2014

NPG Asia Mater

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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 70 lV K À1 , 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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Section: Resultssupporting

confidence: 75%

Efficient thermal spin injection using CoFeAl nanowire

Itoh

Kimura

2014

NPG Asia Mater

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“…This non-local geometry has enabled significant advances in the understanding of spin transport in metals [4][5][6][7][8][9][10][11][12][13][14][15][16]18,22,[24][25][26][27][28][29][30][31][32][33][34][35][36][37] , but has also highlighted serious discrepancies with theory. The primary example of the latter is the surprising non-monotonicity in the temperature (T) dependence of DR NL , and thus the deduced l N , in the transparent interface limit.…”

mentioning

confidence: 99%

“…Surface spin relaxation 10 , reduced dimensions 9 and surface 18 / bulk 8 (magnetic) impurities have all been advanced, but no consensus has emerged. One issue contributing to this is the focus on only a small set of materials, with Ni 80 Fe 20 /Cu and Ni 80 Fe 20 / Ag accounting for a major fraction of prior work 10,18,28,[30][31][32][33][34][35]39 .…”

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confidence: 99%

Kondo physics in non-local metallic spin transport devices

et al. 2014

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The non-local spin-valve is pivotal in spintronics, enabling separation of charge and spin currents, disruptive potential applications and the study of pressing problems in the physics of spin injection and relaxation. Primary among these problems is the perplexing nonmonotonicity in the temperature-dependent spin accumulation in non-local ferromagnetic/ non-magnetic metal structures, where the spin signal decreases at low temperatures. Here we show that this effect is strongly correlated with the ability of the ferromagnetic to form dilute local magnetic moments in the NM. This we achieve by studying a significantly expanded range of ferromagnetic/non-magnetic combinations. We argue that local moments, formed by ferromagnetic/non-magnetic interdiffusion, suppress the injected spin polarization and diffusion length via a manifestation of the Kondo effect, thus explaining all observations. We further show that this suppression can be completely quenched, even at interfaces that are highly susceptible to the effect, by insertion of a thin non-moment-supporting interlayer.

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“…12,13) These experimental developments will open a new way for developing vertical spin transistors with Heusler-alloy source and drain.…”

Section: Growth Of Ge On Heusler Alloysmentioning

confidence: 99%

“…[1][2][3][4] In particular, lots of high-performance full-Heusler alloys have already been reported as ferromagnetic electrodes in magnetic tunnel junctions (MTJs), [5][6][7] current-perpendicular-to-plane giant magnetoresistive (CPP-GMR) structures, [8][9][10][11] and lateral spin valves (LSVs) [12][13][14][15] for the metal-based spintronics. Recently, highly ef cient spin injection and detection in semiconductor layers were explored even for the semiconductor-based spintronics.…”

Section: Introductionmentioning

confidence: 99%

Finely Controlled Approaches to Formation of Heusler-Alloy/Semiconductor Heterostructures for Spintronics

et al. 2016

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We present recent progress of the low-temperature growth of Heusler-alloy/silicon(Si) or Heusler-alloy/germanium(Ge) heterostructures and of their applications for spintronics. First, a concept of the realization of the low-temperature heteroepitaxy for high-quality Heusler alloy/ Si or Heusler alloy/Ge heterostructures is shown. Despite very low-growth temperatures, B2 or L2 1 ordered full-Heusler alloys are achieved. Next, by applying this concept to the growth of Ge on a Heusler alloy or a Heusler alloy on another Heusler alloy, we can also achieve unusual heterostructures for the possibility of novel spintronics applications. Finally, we demonstrate the pure spin current transport in Cu and Ge using these Heusler-alloy spin injectors and detectors. Our approaches will open new avenues for developing high-performance spintronic applications with Heusler alloys.

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Room-temperature generation of giant pure spin currents using epitaxial Co2FeSi spin injectors

Cited by 107 publications

References 28 publications

Efficient thermal spin injection using CoFeAl nanowire

Efficient thermal spin injection using CoFeAl nanowire

Kondo physics in non-local metallic spin transport devices

Finely Controlled Approaches to Formation of Heusler-Alloy/Semiconductor Heterostructures for Spintronics

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