scholarly journals Control of protein activity by photoinduced spin polarized charge reorganization

2021 ◽  
Author(s):  
Shirsendu Ghosh ◽  
Koyel Banerjee Ghosh ◽  
Dorit Levy ◽  
David Scheerer ◽  
Inbal Riven ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Electric Fields ◽  
Protein Function ◽  
Polarized Light ◽  
Phosphoglycerate Kinase ◽  
Charge Injection ◽  
Potential Contribution ◽  
Protein Activity ◽  
Circularly Polarized Light ◽  
Spin Polarized

Biomolecules within the living cell are subject to extensive electrical fields, particularly next to membranes. Indeed, a role for bioelectricity has been well established at the organismal level. While the importance of electrostatics in protein functions such as protein-protein association and enzymatic activity has been well documented, very little is known on how biomolecules respond to external electric fields, or in other words, what may be the potential contribution of polarizability to protein function. Here we use phototriggered charge injection from a site-specifically attached ruthenium photosensitizer to directly demonstrate the effects of charge redistribution within a protein. We find that binding of an antibody to phosphoglycerate kinase (PGK) is increased two folds under illumination. Remarkably, illumination is found to suppress the enzymatic activity of PGK by a factor as large as three. These responses are sensitive to the photosensitizer position on the protein. Surprisingly, left (but not right) circularly polarized light elicits these responses, indicating that the electrons involved in the observed dynamics are spin polarized, due to spin filtration by protein chiral structures. Our results directly establish the contribution of electrical polarization and the importance of the spin-dependent charge reorganization in the function of proteins. Future experiments with phototriggered charge injection will allow delineation of charge rearrangement pathways within proteins and will further depict their effects on protein function.

Optical Pumping and Optical Detection of Spin-Polarized Electrons in a Conduction Band

1971 ◽  
Vol 49 (14) ◽  
pp. 1850-1860 ◽  
Author(s):  
R. R. Parsons
Keyword(s):  
Magnetic Field ◽  
Conduction Band ◽  
Spin Polarization ◽  
Optical Pumping ◽  
Polarized Light ◽  
Degree Of Polarization ◽  
Polarized Electrons ◽  
Excitation Light ◽  
Circularly Polarized Light ◽  
Spin Polarized

Spin-polarized electrons are created in the conduction band of p-type GaSb by excitation with σ+ or σ− circularly polarized light. The degree of polarization of the photoluminescence is used to measure the optically pumped spin polarization. The measurements as a function of transverse magnetic field yield the spin-relaxation time and the lifetime of the photocreated electrons. The degree of polarization oscillates as a function of the photon energy of the excitation light. This effect is associated with mechanisms of rapid energy loss involving optical and acoustical phonons. The optical pumping is studied as a function of temperature in the range 3.5 °K ≤ T ≤ 11 °K. A maximum spin polarization [Formula: see text] is obtained at [Formula: see text]. The efficiency of the optical pumping is significantly increased with the application of a weak longitudinal magnetic field.

Linear and Circular Dichroism in Angle Resolved Fe 3p Photoemission

1994 ◽  
Vol 375 ◽  
Author(s):  
E. Tamura ◽  
G. D. Waddill ◽  
J. G. Tobin ◽  
P. A. Sterne
Keyword(s):  
Polarized Light ◽  
Exchange Splitting ◽  
Orbit Splitting ◽  
Green Function Method ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
X Ray ◽  
Spin Orbit Splitting ◽  
Magnetic Dichroism ◽  
Spin Polarized

AbstractUsing a recently developed spin-polarized, fully relativistic, multiple scattering approach based on the layer KKR Green function method, we have reproduced the Fe 3p angle-resolved soft x-ray photoemission spectra and analyzed the associated large magnetic dichroism effects for excitation with both linearly and circularly polarized light. Comparison between theory and experiment yields a spin-orbit splitting of 1.0 – 1.2 eV and an exchange splitting of 0.9 – 1.0 eV for Fe 3p. These values are 50 – 100 % larger than those hitherto obtained experimentally.

scholarly journals Analysis of Circularly Polarized Light Irradiation Effects on Double Ferromagnetic-Gate Silicene Junction

2018 ◽  
Vol 12 (1) ◽  
pp. 17-25
Author(s):  
Peerasak Chantngarm ◽  
Kou Yamada
Keyword(s):  
Band Structure ◽  
Electric Fields ◽  
Chemical Potential ◽  
Polarized Light ◽  
Light Irradiation ◽  
Main Role ◽  
Exchange Field ◽  
Irradiation Effects ◽  
Circularly Polarized Light ◽  
Circularly Polarized

We present an analytical study of effects that off-resonant circularly polarized light irradiation has on spin-valley currents in dual ferromagnetic-gate silicene-based junctions. Two identical electric fields are applied to both ferromagnetic (FM) gates. Two types of exchange field configurations, parallel (P) and anti-parallel (AP), are applied along with chemical potential to the FM gates in this investigation. The results show that application of circularly polarized light has an impact on polarized spin and valley current characteristics, particularly at the off-resonant frequency region. It also enhances the amplitude of tunnelling magnetoresistance (TMR) significantly. In addition, we found that exchange field configuration has an effect on both spin polarization and valley polarization. Our study reveals that light intensity plays the main role on the light irradiation effects, where the band structure and change electronic properties of the materials are modified by photon dressing to create a new phase of electronic structure. The change of band structure in each region affects the transmission coefficients and transmission probability amplitude of electrons, which in turn affects the conductance of each spin-valley current component. Our study suggests the potential of this scheme in applications, such as spin-valleytronic photo-sensing devices under polarized-photo irradiation.

scholarly journals Deep tuning of photo-thermoelectricity in topological surface states

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shouyuan Huang ◽  
Ireneusz Miotkowski ◽  
Yong P. Chen ◽  
Xianfan Xu
Keyword(s):  
Surface State ◽  
Spin Injection ◽  
Three Dimensional ◽  
Polarized Light ◽  
Surface States ◽  
Linear Dispersion ◽  
Circularly Polarized Light ◽  
Spin Polarized ◽  
Topological Surface ◽  
Topological Surface State

Abstract Three-dimensional topological insulators have been demonstrated in recent years, which possess intriguing gapless, spin-polarized Dirac states with linear dispersion only on the surface. The spin polarization of the topological surface states is also locked to its momentum, which allows controlling motion of electrons using optical helicity, i.e., circularly polarized light. The electrical and thermal transport can also be significantly tuned by the helicity-control of surface state electrons. Here, we report studies of photo-thermoelectric effect of the topological surface states in Bi2Te2Se thin films with large tunability using varied gate voltages and optical helicity. The Seebeck coefficient can be altered by more than five times compared to the case without spin injection. This deep tuning is originated from the optical helicity-induced photocurrent which is shown to be enhanced, reduced, turned off, and even inverted due to the change of the accessed band structures by electrical gating. The helicity-selected topological surface state thus has a large effect on thermoelectric transport, demonstrating great opportunities for realizing helicity control of optoelectronic and thermal devices.

Spin-dependent electron transport in ferromagnet/semiconductor Schottky barrier structures

2000 ◽  
Vol 614 ◽  
Author(s):  
Atsufumi Hirohata ◽  
Yong-Bing Xu ◽  
Christian M. Guertler ◽  
J. Anthony ◽  
C. Bland ◽  
...  
Keyword(s):  
Electron Transport ◽  
Schottky Barrier ◽  
Schottky Barrier Height ◽  
High Efficiency ◽  
Electron Tunneling ◽  
Spin Injection ◽  
Polarized Light ◽  
Film Plane ◽  
Circularly Polarized Light ◽  
Spin Polarized

ABSTRACTClear evidence for high efficiency spin-polarized electron transport across ferromagnet/semiconductor Schottky barrier interfaces was observed in Ni80Fe20/GaAs structures. Circularly polarized light was used to excite electrons with a spin polarization perpendicular to the film plane. At negative bias, an almost constant difference between the helicity-dependent photocurrent obtained for the magnetization parallel and perpendicular to the photon helicity was detected. An effective asymmetry, A, was also estimated from the helicity-dependent photocurrent difference, attributed to spin-polarized electron tunneling from GaAs to NiFe (spin filtering). A decreases with increasing photon energy, which is consistent with the energy-dependence of the asymmetry of photoexcited electrons in GaAs. Weak spin injection from NiFe to GaAs was seen at a bias corresponding to the Schottky barrier height, which is likely to occur via a ballistic process.

scholarly journals Arbitrary helicity control of circularly polarized light from lateral-type spin-polarized light-emitting diodes at room temperature

2018 ◽  
Vol 11 (5) ◽  
pp. 053003 ◽  
Author(s):  
Nozomi Nishizawa ◽  
Masaki Aoyama ◽  
Ronel C. Roca ◽  
Kazuhiro Nishibayashi ◽  
Hiro Munekata
Keyword(s):  
Room Temperature ◽  
Light Emitting Diodes ◽  
Polarized Light ◽  
Circularly Polarized Light ◽  
Light Emitting ◽  
Circularly Polarized ◽  
Spin Polarized

scholarly journals Lateral-Type Spin-Photonics Devices: Development and Applications

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 644
Author(s):  
Nozomi Nishizawa ◽  
Hiro Munekata
Keyword(s):  
Room Temperature ◽  
Polarized Light ◽  
Photonic Devices ◽  
Future Prospects ◽  
Circularly Polarized Light ◽  
Light Emitting ◽  
Current State ◽  
Spin Polarized ◽  
Photonics Devices ◽  
Room Temperature Operation

Spin-photonic devices, represented by spin-polarized light emitting diodes and spin-polarized photodiodes, have great potential for practical use in circularly polarized light (CPL) applications. Focusing on the lateral-type spin-photonic devices that can exchange CPL through their side facets, this review describes their functions in practical CPL applications in terms of: (1) Compactness and integrability, (2) stand-alone (monolithic) nature, (3) room temperature operation, (4) emission with high circular polarization, (5) polarization controllability, and (6) CPL detection. Furthermore, it introduces proposed CPL applications in a wide variety of fields and describes the application of these devices in biological diagnosis using CPL scattering. Finally, it discusses the current state of spin-photonic devices and their applications and future prospects.

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