scholarly journals Proposal to use superparamagnetic nanoparticles to test the role of cryptochrome in magnetoreception

2018 ◽  
Vol 15 (147) ◽  
pp. 20180587 ◽  
Author(s):  
Susannah Bourne Worster ◽  
P. J. Hore
Keyword(s):  
Spin Relaxation ◽  
Spin Dynamics ◽  
Spin Correlation ◽  
Neuronal Firing ◽  
Magnetic Sensors ◽  
Superparamagnetic Nanoparticles ◽  
Magnetic Interactions ◽  
Electron Spin Relaxation ◽  
Primary Sensor ◽  
Dynamics Simulations

Evidence is accumulating to support the hypothesis that some animals use light-induced radical pairs to detect the direction of the Earth's magnetic field. Cryptochrome proteins seem to be involved in the sensory pathway but it is not yet clear if they are the magnetic sensors: they could, instead, play a non-magnetic role as signal transducers downstream of the primary sensor. Here we propose an experiment with the potential to distinguish these functions. The principle is to use superparamagnetic nanoparticles to disable any magnetic sensing role by enhancing the electron spin relaxation of the radicals so as to destroy their spin correlation. We use spin dynamics simulations to show that magnetoferritin, a synthetic, protein-based nanoparticle, has the required properties. If cryptochrome is the primary sensor, then it should be inactivated by a magnetoferritin particle placed 12–16 nm away. This would prevent a bird from using its magnetic compass in behavioural tests and abolish magnetically sensitive neuronal firing in the retina. The key advantage of such an experiment is that any signal transduction role should be completely unaffected by the tiny magnetic interactions (≪ k B T ) required to enhance the spin relaxation of the radical pair.

scholarly journals Discovery and characterization of a new type of domain wall in a row-wise antiferromagnet

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jonas Spethmann ◽  
Martin Grünebohm ◽  
Roland Wiesendanger ◽  
Kirsten von Bergmann ◽  
André Kubetzka
Keyword(s):  
Domain Wall ◽  
Spin Structure ◽  
Domain Walls ◽  
Spin Dynamics ◽  
Magnetic Interactions ◽  
Theoretical Modelling ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
New Type ◽  
Dynamics Simulations

AbstractAntiferromagnets have recently moved into the focus of application-related research, with the perspective to use them in future spintronics devices. At the same time the experimental determination of the detailed spin texture remains challenging. Here we use spin-polarized scanning tunneling microscopy to investigate the spin structure of antiferromagnetic domain walls. Comparison with spin dynamics simulations allows the identification of a new type of domain wall, which is a superposition state of the adjacent domains. We determine the relevant magnetic interactions and derive analytical formulas. Our experiments show a pathway to control the number of domain walls by boundary effects, and demonstrate the possibility to change the position of domain walls by interaction with movable adsorbed atoms. The knowledge about the exact spin structure of the domain walls is crucial for an understanding and theoretical modelling of their properties regarding, for instance, dynamics, response in transport experiments, and manipulation.

scholarly journals Effects of disorder and motion in a radical pair magnetoreceptor

2009 ◽  
Vol 7 (suppl_2) ◽  
Author(s):  
Jason C. S. Lau ◽  
Nicola Wagner-Rundell ◽  
Christopher T. Rodgers ◽  
Nicholas J. B. Green ◽  
P. J. Hore
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Radical Pair ◽  
Experimental Studies ◽  
Magnetic Interactions ◽  
Radical Pairs ◽  
Electron Spin Relaxation ◽  
Effects Of Disorder ◽  
Critical Requirement ◽  
Recombination Reactions

A critical requirement in the proposed chemical model of the avian magnetic compass is that the molecules that play host to the magnetically sensitive radical pair intermediates must be immobilized and rotationally ordered within receptor cells. Rotational disorder would cause the anisotropic responses of differently oriented radical pairs within the same cell to interfere destructively, while rapid molecular rotation would tend to average the crucial anisotropic magnetic interactions and induce electron spin relaxation, reducing the sensitivity to the direction of the geomagnetic field. So far, experimental studies have been able to shed little light on the required degree of ordering and immobilization. To address this question, computer simulations have been performed on a collection of radical pairs undergoing restricted rigid-body rotation, coherent anisotropic spin evolution, electron spin relaxation and spin-selective recombination reactions. It is shown that the ordering and motional constraints necessary for efficient magnetoreception can be simultaneously satisfied if the radical pairs are uniaxially ordered with a moderate order parameter and if their motional correlation time is longer than about a quarter of their lifetime.

Spin dynamics simulation of electron spin relaxation in Ni2 +(aq)

2014 ◽  
Vol 141 (1) ◽  
pp. 014109 ◽  
Author(s):  
Jyrki Rantaharju ◽  
Jiří Mareš ◽  
Juha Vaara
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Spin Dynamics ◽  
Dynamics Simulation ◽  
Electron Spin Relaxation

scholarly journals Actuation of magnetoelastic membranes in precessing magnetic fields

2019 ◽  
Vol 116 (7) ◽  
pp. 2500-2505 ◽  
Author(s):  
Chase Austyn Brisbois ◽  
Mykola Tasinkevych ◽  
Pablo Vázquez-Montejo ◽  
Monica Olvera de la Cruz
Keyword(s):  
Molecular Dynamics ◽  
Magnetic Fields ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Continuum Mechanics ◽  
Superparamagnetic Nanoparticles ◽  
Magnetic Interactions ◽  
Robotic Systems ◽  
Elastic Media ◽  
Dynamics Simulations

Superparamagnetic nanoparticles incorporated into elastic media offer the possibility of creating actuators driven by external fields in a multitude of environments. Here, magnetoelastic membranes are studied through a combination of continuum mechanics and molecular dynamics simulations. We show how induced magnetic interactions affect the buckling and the configuration of magnetoelastic membranes in rapidly precessing magnetic fields. The field, in competition with the bending and stretching of the membrane, transmits forces and torques that drives the membrane to expand, contract, or twist. We identify critical field values that induce spontaneous symmetry breaking as well as field regimes where multiple membrane configurations may be observed. Our insights into buckling mechanisms provide the bases to develop soft, autonomous robotic systems that can be used at micro- and macroscopic length scales.

SPIN DYNAMICS SIMULATIONS OF CLASSICAL, THREE-DIMENSIONAL HEISENBERG MAGNETS

1996 ◽  
Vol 07 (03) ◽  
pp. 401-408 ◽  
Author(s):  
D. P. LANDAU ◽  
ALEX BUNKER ◽  
KUN CHEN
Keyword(s):  
Spin Dynamics ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Finite Size ◽  
Spin Correlation ◽  
Coupled Equations ◽  
Theoretical Predictions ◽  
Dynamics Simulations ◽  
Predictor Corrector ◽  
Good Agreement

Spin dynamics simulations have been used to study dynamic critical behavior of classical Heisenberg magnets. The temporal evolutions of the spin configurations were determined numerically from coupled equations of motion by a fourth-order predictor corrector method, with initial spin configurations generated by Monte-Carlo simulations. The neutron scattering function, S (q, ω), was calculated from the space and time displaced spin-spin correlation function and the dynamic critical exponent z was extracted using dynamic finite size scaling theory. For both ferromagnetic and antiferromagnetic models we find good agreement with theoretical predictions and experimental results.

scholarly journals Electron Spin Relaxation Studies of Polydopamine Radicals

2021 ◽  
Vol 125 (3) ◽  
pp. 841-849 ◽  
Author(s):  
Krzysztof Tadyszak ◽  
Radosław Mrówczyński ◽  
Raanan Carmieli
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Electron Spin Relaxation ◽  
Relaxation Studies

scholarly journals Influence of size polydispersity on magnetic field tunable structures in magnetic nanofluids containing superparamagnetic nanoparticles.

2021 ◽  
Author(s):  
Dillip Kumar Mohapatra ◽  
Philip James Camp ◽  
John Philip
Keyword(s):  
Magnetic Field ◽  
Particle Size ◽  
Light Scattering ◽  
Optical Microscopy ◽  
Brownian Dynamics ◽  
Phase Contrast ◽  
Superparamagnetic Nanoparticles ◽  
Magnetic Nanofluids ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations

We probe the influence of particle size polydispersity on field-induced structures and structural transitions in magnetic fluids (ferrofluids) using phase contrast optical microscopy, light scattering and Brownian dynamics simulations. Three...

Control of the electron spin relaxation by the built-in piezoelectric field in InGaAs quantum wells

2016 ◽  
Vol 108 (8) ◽  
pp. 082103 ◽  
Author(s):  
S. Azaizia ◽  
A. Balocchi ◽  
H. Carrère ◽  
P. Renucci ◽  
T. Amand ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Spin Relaxation ◽  
Electron Spin ◽  
Electron Spin Relaxation ◽  
Piezoelectric Field
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