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Photospintronics: Magnetic Field-Controlled Photoemission and Light-Controlled Spin Transport in Hybrid Chiral Oligopeptide-Nanoparticle Structures.

Mondal PC, Roy P, Kim D, Fullerton EE, Cohen H, Naaman R - Nano Lett. (2016)

Bottom Line: It is shown here that in systems in which organic molecules and semiconductor nanoparticles are combined, matching these technologies results in interesting new phenomena.We report on light induced and spin-dependent charge transfer process through helical oligopeptide-CdSe nanoparticles' (NPs) architectures deposited on ferromagnetic substrates with small coercive force (∼100-200 Oe).By switching the direction of the magnetic field of the substrate, the PL intensity could be alternated.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Physics, Weizmann Institute of Science , Rehovot 76100, Israel.

ABSTRACT
The combination of photonics and spintronics opens new ways to transfer and process information. It is shown here that in systems in which organic molecules and semiconductor nanoparticles are combined, matching these technologies results in interesting new phenomena. We report on light induced and spin-dependent charge transfer process through helical oligopeptide-CdSe nanoparticles' (NPs) architectures deposited on ferromagnetic substrates with small coercive force (∼100-200 Oe). The spin control is achieved by the application of the chirality-induced spin-dependent electron transfer effect and is probed by two different methods: spin-controlled electrochemichemistry and photoluminescence (PL) at room temperature. The injected spin could be controlled by excitation of the nanoparticles. By switching the direction of the magnetic field of the substrate, the PL intensity could be alternated.

No MeSH data available.


(A) Schematic presentation of the experimentalsetup for the spin-dependent photoluminescence measurements. (B) Schematicpresentation of the light-induced spin-dependent electrochemical measurementsrecorded in a homemade electrochemical cell in the presence of trisbuffer containing 5 mM K4[Fe(CN)6]/K3[Fe(CN)6]. The ferromagnetic substrate was the workingelectrode (WE), whereas platinum wire and KCl-saturated calomel electrode(SCE) were used as the counter (CE) and reference (RE) electrodes,respectively. The working electrode was based on multiple ferromagneticlayers, and it was coated with the Ala8–CdSe NP assemblies.In both cases, a permanent magnet (H = 0.35 T) wasplaced underneath the modified ferromagnetic substrate and the directionof the magnetic dipole was flipped either pointing “UP”or “DOWN” (white and yellow arrows, respectively). Inall cases, a green laser (λexc = 514 nm) was usedfor exciting the CdSe NPs.
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fig1: (A) Schematic presentation of the experimentalsetup for the spin-dependent photoluminescence measurements. (B) Schematicpresentation of the light-induced spin-dependent electrochemical measurementsrecorded in a homemade electrochemical cell in the presence of trisbuffer containing 5 mM K4[Fe(CN)6]/K3[Fe(CN)6]. The ferromagnetic substrate was the workingelectrode (WE), whereas platinum wire and KCl-saturated calomel electrode(SCE) were used as the counter (CE) and reference (RE) electrodes,respectively. The working electrode was based on multiple ferromagneticlayers, and it was coated with the Ala8–CdSe NP assemblies.In both cases, a permanent magnet (H = 0.35 T) wasplaced underneath the modified ferromagnetic substrate and the directionof the magnetic dipole was flipped either pointing “UP”or “DOWN” (white and yellow arrows, respectively). Inall cases, a green laser (λexc = 514 nm) was usedfor exciting the CdSe NPs.

Mentions: The concept of controllingmagnetism by light has attracted much attention in recent years.1−3 Specifically, the controlling of spin transport by light combinestwo interesting technologies, photonics and spintronics.4,5 Having organic material makes the coupling of the two technologieseasier6−8 because the light-absorbing properties of organicmolecules can be modified relatively easily.9,10 Recently,it was found that the transmission of electrons through chiral moleculesdepends on the electrons’ spin orientation; this effect isreferred to as chiral-induced spin selectivity (CISS).11,12 The CISS effect makes it possible to construct spintronic deviceswithout ferromagnetic spin injectors because the chiral moleculesthemselves serve to select a specific spin to transport across themolecules.13−16 In the hybrid system studied herein, helical oligopeptide moleculeswere attached on one end to CdSe nanoparticles (NPs) and on the otherend to ferromagnetic substrates. Two experimental configurations wereapplied; in the first, the photoemission intensity from the NPs wasmonitored as a function of the magnetization direction of the substrate(Figure 1A). In addition,electrochemical measurements were conducted (Figure 1B) when the ferromagnetic working electrodewas coated with the oligopeptide–CdSe NP system. The faradiccurrent through the adsorbed layer was measured as a function of thedirection of the magnetic field when the system was illuminated. Itwas established that when an electron is transmitted through a chiralmolecule, a specific spin orientation is preferred. Here, we utilizedthe effect to control the photoluminescence (PL) intensity from theNPs by controlling the direction of the magnetic field of the substrate.We also demonstrated control by light of the preferred spin transmittedthrough the structures of hybrid chiral molecules–NPs.


Photospintronics: Magnetic Field-Controlled Photoemission and Light-Controlled Spin Transport in Hybrid Chiral Oligopeptide-Nanoparticle Structures.

Mondal PC, Roy P, Kim D, Fullerton EE, Cohen H, Naaman R - Nano Lett. (2016)

(A) Schematic presentation of the experimentalsetup for the spin-dependent photoluminescence measurements. (B) Schematicpresentation of the light-induced spin-dependent electrochemical measurementsrecorded in a homemade electrochemical cell in the presence of trisbuffer containing 5 mM K4[Fe(CN)6]/K3[Fe(CN)6]. The ferromagnetic substrate was the workingelectrode (WE), whereas platinum wire and KCl-saturated calomel electrode(SCE) were used as the counter (CE) and reference (RE) electrodes,respectively. The working electrode was based on multiple ferromagneticlayers, and it was coated with the Ala8–CdSe NP assemblies.In both cases, a permanent magnet (H = 0.35 T) wasplaced underneath the modified ferromagnetic substrate and the directionof the magnetic dipole was flipped either pointing “UP”or “DOWN” (white and yellow arrows, respectively). Inall cases, a green laser (λexc = 514 nm) was usedfor exciting the CdSe NPs.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834632&req=5

fig1: (A) Schematic presentation of the experimentalsetup for the spin-dependent photoluminescence measurements. (B) Schematicpresentation of the light-induced spin-dependent electrochemical measurementsrecorded in a homemade electrochemical cell in the presence of trisbuffer containing 5 mM K4[Fe(CN)6]/K3[Fe(CN)6]. The ferromagnetic substrate was the workingelectrode (WE), whereas platinum wire and KCl-saturated calomel electrode(SCE) were used as the counter (CE) and reference (RE) electrodes,respectively. The working electrode was based on multiple ferromagneticlayers, and it was coated with the Ala8–CdSe NP assemblies.In both cases, a permanent magnet (H = 0.35 T) wasplaced underneath the modified ferromagnetic substrate and the directionof the magnetic dipole was flipped either pointing “UP”or “DOWN” (white and yellow arrows, respectively). Inall cases, a green laser (λexc = 514 nm) was usedfor exciting the CdSe NPs.
Mentions: The concept of controllingmagnetism by light has attracted much attention in recent years.1−3 Specifically, the controlling of spin transport by light combinestwo interesting technologies, photonics and spintronics.4,5 Having organic material makes the coupling of the two technologieseasier6−8 because the light-absorbing properties of organicmolecules can be modified relatively easily.9,10 Recently,it was found that the transmission of electrons through chiral moleculesdepends on the electrons’ spin orientation; this effect isreferred to as chiral-induced spin selectivity (CISS).11,12 The CISS effect makes it possible to construct spintronic deviceswithout ferromagnetic spin injectors because the chiral moleculesthemselves serve to select a specific spin to transport across themolecules.13−16 In the hybrid system studied herein, helical oligopeptide moleculeswere attached on one end to CdSe nanoparticles (NPs) and on the otherend to ferromagnetic substrates. Two experimental configurations wereapplied; in the first, the photoemission intensity from the NPs wasmonitored as a function of the magnetization direction of the substrate(Figure 1A). In addition,electrochemical measurements were conducted (Figure 1B) when the ferromagnetic working electrodewas coated with the oligopeptide–CdSe NP system. The faradiccurrent through the adsorbed layer was measured as a function of thedirection of the magnetic field when the system was illuminated. Itwas established that when an electron is transmitted through a chiralmolecule, a specific spin orientation is preferred. Here, we utilizedthe effect to control the photoluminescence (PL) intensity from theNPs by controlling the direction of the magnetic field of the substrate.We also demonstrated control by light of the preferred spin transmittedthrough the structures of hybrid chiral molecules–NPs.

Bottom Line: It is shown here that in systems in which organic molecules and semiconductor nanoparticles are combined, matching these technologies results in interesting new phenomena.We report on light induced and spin-dependent charge transfer process through helical oligopeptide-CdSe nanoparticles' (NPs) architectures deposited on ferromagnetic substrates with small coercive force (∼100-200 Oe).By switching the direction of the magnetic field of the substrate, the PL intensity could be alternated.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Physics, Weizmann Institute of Science , Rehovot 76100, Israel.

ABSTRACT
The combination of photonics and spintronics opens new ways to transfer and process information. It is shown here that in systems in which organic molecules and semiconductor nanoparticles are combined, matching these technologies results in interesting new phenomena. We report on light induced and spin-dependent charge transfer process through helical oligopeptide-CdSe nanoparticles' (NPs) architectures deposited on ferromagnetic substrates with small coercive force (∼100-200 Oe). The spin control is achieved by the application of the chirality-induced spin-dependent electron transfer effect and is probed by two different methods: spin-controlled electrochemichemistry and photoluminescence (PL) at room temperature. The injected spin could be controlled by excitation of the nanoparticles. By switching the direction of the magnetic field of the substrate, the PL intensity could be alternated.

No MeSH data available.