FQM367 - Artículoshttps://hdl.handle.net/10481/492562024-03-29T01:02:23Z2024-03-29T01:02:23ZChirality-Induced Spin Selectivity in Supramolecular Chirally Functionalized GrapheneFirouzeh, SeyedaminIllescas Lopez, SaraHossain, Md. AnikCuerva Carvajal, Juan ManuelÁlvarez de Cienfuegos Rodríguez, LuisPramanik, Sandipanhttps://hdl.handle.net/10481/843112023-09-07T09:54:11ZChirality-Induced Spin Selectivity in Supramolecular Chirally Functionalized Graphene
Firouzeh, Seyedamin; Illescas Lopez, Sara; Hossain, Md. Anik; Cuerva Carvajal, Juan Manuel; Álvarez de Cienfuegos Rodríguez, Luis; Pramanik, Sandipan
Chiral graphene hybrid materials have attracted significant attention in recent years due to their
various applications in the areas of chiral catalysis, chiral separation and recognition, enantioselective sensing, etc.
On the other hand, chiral materials are also known to exhibit chirality-dependent spin transmission, commonly
dubbed “chirality induced spin selectivity” or CISS. However, CISS properties of chiral graphene materials are
largely unexplored. As such, it is not clear whether graphene is even a promising material for the CISS effect given its
weak spin−orbit interaction. Here, we report the CISS effect in chiral graphene sheets, in which a graphene
derivative (reduced graphene oxide or rGO) is noncovalently functionalized with chiral Fmoc-FF (Fmocdiphenylalanine) supramolecular fibers. The graphene flakes acquire a “conformational chirality” postfunctionalization, which, combined with other factors, is presumably responsible for the CISS signal. The CISS signal correlates
with the supramolecular chirality of the medium, which depends on the thickness of graphene used. Quite
interestingly, the noncovalent supramolecular chiral functionalization of conductive materials offers a simple and
straightforward methodology to induce chirality and CISS properties in a multitude of easily accessible advanced
conductive materials.
Chirality-induced Spin Selectivity in Functionalized Carbon Nanotube Networks: The Role of Spin-orbit CouplingFirouzeh, SeyedaminIllescas Lopez, SaraHossain, Md. AnikCuerva Carvajal, Juan ManuelÁlvarez Cienfuegos Rodríguez, LuisPramanik, Sandipanhttps://hdl.handle.net/10481/839162023-07-21T11:37:14ZChirality-induced Spin Selectivity in Functionalized Carbon Nanotube Networks: The Role of Spin-orbit Coupling
Firouzeh, Seyedamin; Illescas Lopez, Sara; Hossain, Md. Anik; Cuerva Carvajal, Juan Manuel; Álvarez Cienfuegos Rodríguez, Luis; Pramanik, Sandipan
Spin–orbit coupling in a chiral medium is generally assumed to be a necessary ingredient for the observation of the chirality-induced spin selectivity (CISS) effect. However, some recent studies have suggested that CISS may manifest even when the chiral medium has zero spin–orbit coupling. In such systems, CISS may arise due to an orbital polarization effect, which generates an electromagnetochiral anisotropy in two-terminal conductance. Here, we examine these concepts using a chirally functionalized carbon nanotube network as the chiral medium. A transverse measurement geometry is used, which nullifies any electromagnetochiral contribution but still exhibits the tell-tale signs of the CISS effect. This suggests that CISS may not be explained solely by electromagnetochiral effects. The role of nanotube spin–orbit coupling on the observed pure CISS signal is studied by systematically varying nanotube diameter. We find that the magnitude of the CISS signal scales proportionately with the spin–orbit coupling strength of the nanotubes. We also find that nanotube diameter dictates the supramolecular chirality of the medium, which in turn determines the sign of the CISS signal.
Transverse Magnetoconductance in Two-Terminal Chiral Spin-Selective DevicesHossain, Md. AnikIllescas Lopez, SaraNair, RahulCuerva Carvajal, Juan ManuelÁlvarez Cienfuegos Rodríguez, LuisPramanik, Sandipanhttps://hdl.handle.net/10481/799032023-02-14T07:33:07ZTransverse Magnetoconductance in Two-Terminal Chiral Spin-Selective Devices
Hossain, Md. Anik; Illescas Lopez, Sara; Nair, Rahul; Cuerva Carvajal, Juan Manuel; Álvarez Cienfuegos Rodríguez, Luis; Pramanik, Sandipan
The phenomenon of chirality induced spin selectivity (CISS) has triggered significant activity in recent years, although many aspects of it remain to be understood. For example, most investigations are focused on spin polarizations collinear to the charge current, and hence longitudinal magnetoconductance (MC) is commonly studied in two-terminal transport experiments. Very little is known about the transverse spin components and transverse MC – their existence, as well as any dependence of this component on chirality. Further, measurement of the CISS effect via two-terminal MC experiments remains a controversial topic. Detection of this effect in the linear response regime is debated, with contradicting reports in the literature. Finally, potential influence of the well-known electric magnetochiral effect on CISS remains unclear. To shed light on these issues, in this work we have investigated the bias dependence of the CISS effect using planar carbon nanotube networks functionalized with chiral molecules. We find that (a) transverse MC exists and exhibits tell-tale signs of the CISS effect, (b) transverse CISS MC vanishes in the linear response regime establishing the validity of Onsager’s relation in two-terminal CISS systems, and finally (c) CISS signal remains present even in the absence of electric magneto chiral effects, suggesting existence of an alternative physical origin of CISS MC.
Chirality-induced Spin Selectivity in Heterochiral Short-Peptide-Carbon Nanotube Hybrid Networks – Role of SupramolecularRahman, Md. WazedurMañas Torres, María del CarmenFirouzeh, SeyedaminIllescas Lopez, SaraCuerva Carvajal, Juan ManuelLópez López, Modesto TorcuatoÁlvarez Cienfuegos Rodríguez, LuisPramanik, Sandipanhttps://hdl.handle.net/10481/767222023-03-09T12:43:33ZChirality-induced Spin Selectivity in Heterochiral Short-Peptide-Carbon Nanotube Hybrid Networks – Role of Supramolecular
Rahman, Md. Wazedur; Mañas Torres, María del Carmen; Firouzeh, Seyedamin; Illescas Lopez, Sara; Cuerva Carvajal, Juan Manuel; López López, Modesto Torcuato; Álvarez Cienfuegos Rodríguez, Luis; Pramanik, Sandipan
Supramolecular short-peptide assemblies have been widely used for the development of biomaterials with potential biomedical applications. These peptides can self-assemble in multitude of chiral hierarchical structures triggered by the application of different stimuli, such as changes in temperature, pH, solvent, etc. The self-assembly process is very susceptible to the chemical composition of the peptides, being affected by specific amino acid sequence, type and chirality. The resulting supramolecular chirality of these materials has been explored to modulate protein and cell interactions. Recently, significant attention has been focused on the development of chiral materials with potential spintronic applications as it has been shown that transport of charge carriers through a chiral environment polarizes the carrier spins. This effect, named Chirality Induced Spin Selectivity or CISS, has been studied in different chiral organic molecules and materials, as well as carbon nanotubes functionalized with chiral molecules. Nevertheless, this effect has been only explored in homochiral systems in which the chirality of the medium, and hence the resulting spin polarization, is defined by the chirality of the molecule, with limited options for tunability. Herein, we have developed heterochiral carbon nanotube-short-peptide materials made by the combination of two different chiral sources, that is, homochiral peptides (L/D) + glucono-δ-lactone. We show that the presence of a small amount of glucono-δ-lactone with fixed chirality can alter the supramolecular chirality of the medium, thereby modulating the sign of the spin signal from “up” to “down” and vice versa. In addition, small amounts of glucono-δ-lactone can even induce non-zero spin polarization in an otherwise achiral and spin-inactive peptide-nanotube composite. Such “chiral doping” strategies could allow development of complimentary spintronic devices on a single material platform, opening novel design directions for CISS-based spintronic devices and circuits.
Molecular Functionalization and Emergence of Long-range Spin-dependent Phenomena in Two-dimensional (2D) Carbon Nanotube NetworksRahman, Md. WazedurMañas Torres, María del CarmenFirouzeh, SeyedaminCuerva Carvajal, Juan ManuelÁlvarez Cienfuegos Rodríguez, LuisPramanik, Sandipanhttps://hdl.handle.net/10481/747652022-05-10T06:51:16ZMolecular Functionalization and Emergence of Long-range Spin-dependent Phenomena in Two-dimensional (2D) Carbon Nanotube Networks
Rahman, Md. Wazedur; Mañas Torres, María del Carmen; Firouzeh, Seyedamin; Cuerva Carvajal, Juan Manuel; Álvarez Cienfuegos Rodríguez, Luis; Pramanik, Sandipan
Molecular functionalization of CNTs is a routine procedure in
the field of nanotechnology. However, whether and how these molecules affect
the spin polarization of the charge carriers in CNTs are largely unknown. In
this work we demonstrate that spin polarization can indeed be induced in twodimensional
(2D) CNT networks by “certain” molecules and the spin signal
routinely survives length scales significantly exceeding 1 μm. This result
effectively connects the area of molecular spintronics with that of carbon-based
2D nanoelectronics. By using the versatility of peptide chemistry, we further
demonstrate how spin polarization depends on molecular structural features
such as chirality as well as molecule−nanotube interactions. A chiralityindependent
effect was detected in addition to the more common chiralitydependent
effect, and the overall spin signal was found to be a combination of
both. Finally, the magnetic field dependence of the spin signals has been
explored, and the “chirality-dependent” signal has been found to exist only in
certain field angles.