NRL Researchers First to Detect Spin Precession in Silicon Nanowires

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Silicon nanowire. Image source: Wikimedia Commons

Scientists during a U.S. Naval Research Laboratory (NRL) have reported a initial regard of spin precession of spin currents issuing in a silicon nanowire (NW) ride channel, and dynamic spin lifetimes and analogous spin freeing lengths in these nanoscale spintronic devices. The spin currents were electrically injected and rescued regulating ferromagnetic steel contacts with a hovel separator consisting of singular covering graphene between a steel and silicon NW.

False tone atomic force microscopy picture of a silicon nanowire with a 4 contacts used in a spin measurements. The ferromagnetic steel / graphene hovel separator contacts used to inject and detect spin seem as blue, a bullion ohmic anxiety contacts seem as yellow, and a immature line is a silicon nanowire ride channel. The splendid dot on a finish of a nanowire is a bullion nanoparticle used to seed a nanowire growth. (Photo: U.S. Naval Research Laboratory)

False tone atomic force microscopy picture of a silicon nanowire with a 4 contacts used in a spin measurements. The ferromagnetic steel / graphene hovel separator contacts used to inject and detect spin seem as blue, a bullion ohmic anxiety contacts seem as yellow, and a immature line is a silicon nanowire ride channel. The splendid dot on a finish of a nanowire is a bullion nanoparticle used to seed a nanowire growth.
(Photo: U.S. Naval Research Laboratory)

The NRL investigate group celebrated spin precession (the Hanle effect) for both a spin-polarized assign nearby a hit interface and for pristine spin currents issuing in a NW channel. The latter unambiguously shows that spins have been injected and ecstatic in a Si NW. The use of graphene as a hovel separator provides a low-resistance area product hit and purify captivating switching characteristics, since it uniformly bridges a NW and minimizes difficult captivating domains that differently concede a captivating behavior. The team’s find is an essential step toward a fulfilment of rarely scaled semiconductor spintronic devices. The investigate formula are reported in a 19 Jun 2015 emanate of Nature Communications (DOI 10.1038/ncomms8541).

 

Semiconductor nanowires produce an entrance to serve revoke a ever-shrinking measure of transistors. Including nucleus spin as an additional state non-static offers new prospects for information processing, enabling destiny non-volatile, reprogrammable inclination over a stream semiconductor record roadmap. Silicon is an ideal horde for such a spin-based record since a unique properties foster spin transport, explains principal questioner Dr. Olaf van’t Erve.

Realization of spin-based Si NW inclination requires fit electrical spin injection and detection, that count critically on a interface insurgency between a ferromagnetic steel hit and a NW. This is generally cryptic with semiconducting NWs since of a awfully tiny hit area, that can be of sequence 100 nm2. Researchers have shown customary oxide hovel barriers to produce good spin injection into planar Si structures, though such contacts grown on NWs are mostly too resistive to produce arguable and unchanging results. The NRL group grown and used a graphene hovel separator hit that produces glorious spin injection and also satisfies several pivotal technical criteria: it provides a low resistance-area product, a rarely uniform hovel covering with well-controlled thickness, purify captivating switching characteristics for a captivating contacts, and harmony with both a ferromagnetic steel and silicon NW.

Schematic of a 4 depot nanowire device in a non-local spin valve geometry. A spin-polarized assign stream is injected during a left red NiFe/graphene ferromagnetic contact, generating a pristine spin stream that flows to a right within a silicon nanowire. This spin stream generates a voltage that is rescued on a right ferromagnetic contact. (Photo: U.S. Naval Research Laboratory) 

Schematic of a 4 depot nanowire device in a non-local spin valve geometry. A spin-polarized assign stream is injected during a left red NiFe/graphene ferromagnetic contact, generating a pristine spin stream that flows to a right within a silicon nanowire. This spin stream generates a voltage that is rescued on a right ferromagnetic contact.
(Photo: U.S. Naval Research Laboratory)

Using unique 2D layers such as graphene or hexagonal boron nitride as hovel contacts on nanowires offers many advantages over required materials deposited by fog deposition (such as Al2O3 or MgO), enabling a trail to rarely scaled electronic and spintronic devices. The use of multilayer rather than singular covering graphene in such structures might produce most aloft values of a hovel spin polarization since of rope structure subsequent spin filtering effects likely for comparison ferromagnetic steel / multi-layer graphene structures. This boost would serve urge a opening of nanowire spintronic inclination by providing aloft vigilance to sound ratios and analogous handling speeds, advancing a techological applications of nanowire devices.

Source: NRL