Magnetic properties of epitaxially grown Fe3Si/Ge(111) layers with atomically flat heterointerfaces

Ando, Yoshinori; Hamaya, Kohei; Kasahara, Kenji; Ueda, Kazuyuki; Nozaki, Yukio; Sadoh, Taizoh; Maeda, Yoshihito; Matsuyama, K.; Miyao, Masanobu

doi:10.1063/1.3065985

Cited by 43 publications

(52 citation statements)

References 20 publications

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“…[10] These facts also support that the presence of the in-plane uniaxial anisotropy is probably caused by the high-quality Co 2 FeSi/Si(111) interfaces.…”

Section: Pacs Numberssupporting

confidence: 69%

“…This uniaxial anisotropy cannot be explained only by the magnetocrystalline anisotropy of the single-crystal Co 2 FeSi/Si(111), since it has sixfold crystal symmetry in the film plane. In our previous works, we have already observed a similar in-plane uniaxial anisotropy for Fe 3 Si/Ge(111) and Fe 3 Si/Si(111) epilayers with high-quality heterointerfaces, [10] however, its precise origin is still unclear. For both cases, once the interlayers such as FeGe and FeSi were observed at the heterointerfaces, the above uniaxial anisotropy vanished.…”

Section: Pacs Numbersmentioning

confidence: 97%

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Epitaxial growth of a full-Heusler alloy Co2FeSi on silicon by low-temperature molecular beam epitaxy

et al. 2010

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For electrical spin injection and detection of spin-polarized electrons in silicon, we explore highly epitaxial growth of ferromagnetic full-Heusler-alloy Co2FeSi thin films on silicon substrates using low-temperature molecular beam epitaxy (LTMBE). Although in-situ reflection high energy electron diffraction images clearly show two-dimensional epitaxial growth for growth temperatures (TG) of 60, 130, and 200• C, cross-sectional transmission electron microscopy experiments reveal that there are single-crystal phases other than Heusler alloys near the interface between Co2FeSi and Si for TG = 130 and 200• C. On the other hand, almost perfect heterointerfaces are achieved for TG = 60 • C. These results and magnetic measurements indicate that highly epitaxial growth of Co2FeSi thin films on Si is demonstrated only for TG = 60• C.

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“…[10] These facts also support that the presence of the in-plane uniaxial anisotropy is probably caused by the high-quality Co 2 FeSi/Si(111) interfaces.…”

Section: Pacs Numberssupporting

confidence: 69%

Section: Pacs Numbersmentioning

confidence: 97%

Epitaxial growth of a full-Heusler alloy Co2FeSi on silicon by low-temperature molecular beam epitaxy

et al. 2010

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“…[20] In addition, it is well known that such complicated in-plane anisotropies can affect in-plane magnetic configurations for epitaxially grown ferromagnetic thin films in various external magnetic fields. [21,22] Namely, if the applied field direction, which is nearly parallel to the long axis of the wire-shaped Fe 3 Si injector and detector, is deviated from its magnetic easy axis, we could not get precise parallel and anti-parallel configurations at zero field and at a magnetization switching field, respectively.…”

Section: Pacs Numbersmentioning

confidence: 99%

Electrical injection and detection of spin-polarized electrons in silicon through an Fe3Si/Si Schottky tunnel barrier

Ando

Hamaya

Kasahara

et al. 2009

Applied Physics Letters

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133

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We demonstrate electrical injection and detection of spin-polarized electrons in silicon (Si) using epitaxially grown Fe3Si/Si Schottky-tunnel-barrier contacts. By an insertion of a δ-doped n + -Si layer (∼ 10 19 cm −3 ) near the interface between a ferromagnetic Fe3Si contact and a Si channel (∼ 10 15 cm −3 ), we achieve a marked enhancement in the tunnel conductance for reverse-bias characteristics of the Fe3Si/Si Schottky diodes. Using laterally fabricated four-probe geometries with the modified Fe3Si/Si contacts, we detect nonlocal output signals which originate from the spin accumulation in a Si channel at low temperatures. PACS numbers:To solve critical issues caused by the scaling limit of complementary metal-oxide-semiconductor (CMOS) technologies, spin-based electronics (spintronics) has been studied.[1] For semiconductor spintronic applications, an electrical spin injection from a ferromagnet (FM) into a semiconductor (SC) and its detection are crucial techniques.Recently, methods for spin injection and/or detection in silicon (Si) were explored intensely [2,3,4,5,6,7] because Si has a long spin relaxation time and is compatible with the current industrial semiconductor technologies. Although electrical detections of spin transport in Si conduction channels were demonstrated by two research groups, [4,5] an insulating Al 2 O 3 tunnel barrier between FM and Si was utilized for efficient spin injection and/or detection. To realize gate-tunable spin devices, e.g., spin metal-oxidesemiconductor field effect transistors (spin MOSFET), [8] demonstrations of electrical spin injection and detection in Si conduction channels using Schottky tunnel-barrier contacts will become considerably important. [9,10] By low-temperature molecular beam epitaxy (LTMBE), we recently demonstrated highly epitaxial growth of a binary Heusler alloy Fe 3 Si on Si and obtained an atomically abrupt heterointerface. [11] In this letter, inserting a heavily doped n + -Si layer near the abrupt interface between Fe 3 Si and n-Si, we achieve an effective Shottky tunnel barrier for spin injection into Si. Using nonlocal signal measurements, we demonstrate electrical injection and detection of spin-polarized electrons in Si conduction channels though the Schottky-tunnel-barrier contacts.The n + -Si layer was formed on n-Si(111) (n ∼ 4.5 × 10 15 cm −3 ) by a combination of the Si solid-phase epitaxy with an Sb δ-doping process, [12] where the carrier * E-mail: hamaya@ed.kyushu-u.ac.jp † E-mail: miyao@ed.kyushu-u.ac.jp concentration of the n + -Si layer was ∼ 2.3 × 10 19 cm −3 , determined by Hall effect measurements, and ∼ 10-nmthick non-doped Si layer was grown on the Sb δ-doped layer. Ferromagnetic Fe 3 Si layers with a thickness of ∼ 50 nm were grown by LTMBE at 130 • C, as shown in our previous work.[11] The interface between Fe 3 Si and n + -Si was comparable to that shown in Ref. 11. To evaluate electrical properties of the Fe 3 Si/Si Schottky contacts, we firstly fabricated two different Schottky diodes (∼ 1 mm in diameter) with and w...

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“…Magnetization curves with twostep behavior were reproducibly observed for many samples, and the top Fe 3 Si layers showed unexpected large coercivity of ~1.0 mT. Since we have observed unexpected in-plane anisotropy of D0 3 -Fe 3 Si layers on Ge, 50) we now speculate that there is an interfacial magnetic anisotropy between the top Fe 3 Si layer and the grown Ge epilayer. We will explore the detection of the spin-dependent transport in the vertical Gebased spin devices.…”

Section: Growth Of Ge On Heusler Alloysmentioning

confidence: 80%

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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Magnetic properties of epitaxially grown Fe3Si/Ge(111) layers with atomically flat heterointerfaces

Cited by 43 publications

References 20 publications

Epitaxial growth of a full-Heusler alloy Co2FeSi on silicon by low-temperature molecular beam epitaxy

Epitaxial growth of a full-Heusler alloy Co2FeSi on silicon by low-temperature molecular beam epitaxy

Electrical injection and detection of spin-polarized electrons in silicon through an Fe3Si/Si Schottky tunnel barrier

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

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