Use of the Faraday optical transformer for ultrafast magnetization reversal of nanomagnets

Kruglyak, V. V.; Portnoi, M. E.; Hicken, R. J.

doi:10.1117/1.2516174

Cited by 16 publications

(10 citation statements)

References 27 publications

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“…We now evaluate the magnetic field induced by a coherent ring current since magnetic flux is a control parameter for switching devices as well as the ring current. [50][51][52] There have been several reports on calculations of magnetic fields of molecules in intense laser pulses. [53][54][55] The magnetic flux density along the central axis perpendicular to ring K (=L or R) is given in a simple ring loop (SRL) model as…”

Section: Coherent Ring Current-induced Magnetic Fieldmentioning

confidence: 99%

Coherent π-electron dynamics of (P)-2,2′-biphenol induced by ultrashort linearly polarized UV pulses: Angular momentum and ring current

Mineo

Lin

Fujimura

2013

The Journal of Chemical Physics

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The results of a theoretical investigation of coherent π-electron dynamics for nonplanar (P)-2,2'-biphenol induced by ultrashort linearly polarized UV pulses are presented. Expressions for the time-dependent coherent angular momentum and ring current are derived by using the density matrix method. The time dependence of these coherences is determined by the off-diagonal density matrix element, which can be obtained by solving the coupled equations of motion of the electronic-state density matrix. Dephasing effects on coherent angular momentum and ring current are taken into account within the Markov approximation. The magnitudes of the electronic angular momentum and current are expressed as the sum of expectation values of the corresponding operators in the two phenol rings (L and R rings). Here, L (R) denotes the phenol ring in the left (right)-hand side of (P)-2,2'-biphenol. We define the bond current between the nearest neighbor carbon atoms Ci and Cj as an electric current through a half plane perpendicular to the Ci-Cj bond. The bond current can be expressed in terms of the inter-atomic bond current. The inter-atomic bond current (bond current) depends on the position of the half plane on the bond and has the maximum value at the center. The coherent ring current in each ring is defined by averaging over the bond currents. Since (P)-2,2'-biphenol is nonplanar, the resultant angular momentum is not one-dimensional. Simulations of the time-dependent coherent angular momentum and ring current of (P)-2,2'-biphenol excited by ultrashort linearly polarized UV pulses are carried out using the molecular parameters obtained by the time-dependent density functional theory (TD-DFT) method. Oscillatory behaviors in the time-dependent angular momentum (ring current), which can be called angular momentum (ring current) quantum beats, are classified by the symmetry of the coherent state, symmetric or antisymmetric. The bond current of the bridge bond linking the L and R rings is zero for the symmetric coherent state, while it is nonzero for the antisymmetric coherent state. The magnitudes of ring current and ring current-induced magnetic field are also evaluated, and their possibility as a control parameter in ultrafast switching devices is discussed. The present results give a detailed description of the theoretical treatment reported in our previous paper [H. Mineo, M. Yamaki, Y. Teranish, M. Hayashi, S. H. Lin, and Y. Fujimura, J. Am. Chem. Soc. 134, 14279 (2012)].

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Section: Coherent Ring Current-induced Magnetic Fieldmentioning

confidence: 99%

Coherent π-electron dynamics of (P)-2,2′-biphenol induced by ultrashort linearly polarized UV pulses: Angular momentum and ring current

Mineo

Lin

Fujimura

2013

The Journal of Chemical Physics

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“…We estimated the magnetic fields (magnetic field flux density) generated by the coherent ring currents of (P)-2,2'-biphenol. The results may provide fundamental information for designing ultrafast switching devices controlled by current-induced magnetic fields as well as coherent ring currents [52][53][54].…”

Section: Coherent Ring Current-induced Magnetic Fieldmentioning

confidence: 94%

Quantum Control of Coherent π-Electron Dynamics in Aromatic Ring Molecules

2021

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Herein we review a theoretical study of unidirectional π-electron rotation in aromatic ring molecules, which originates from two quasi-degenerate electronic excited states created coherently by a linearly polarized ultraviolet/visible laser with a properly designed photon polarization direction. Analytical expressions for coherent π-electron angular momentum, ring current and ring current-induced magnetic field are derived in the quantum chemical molecular orbital (MO) theory. The time evolution of the angular momentum and the ring current are expressed using the density matrix method under Markov approximation or by solving the time-dependent Schrödinger equation. In this review we present the results of the following quantum control scenarios after a fundamental theoretical description of coherent angular momentum, ring current and magnetic field: first, two-dimensional coherent π-electron dynamics in a non-planar (P)-2,2’-biphenol molecule; second, localization of the coherent π-electron ring current to a designated benzene ring in polycyclic aromatic hydrocarbons; third, unidirectional π-electron rotations in low-symmetry aromatic ring molecules based on the dynamic Stark shift of two relevant excited states that form a degenerate state using the non-resonant ultraviolet lasers. The magnetic fields induced by the coherent π-electron ring currents are also estimated, and the position dependence of the magnetic fluxes is demonstrated.

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“…The phase factors in Eqs. (32) are taken in such a way that functionsχ N andχ N +1 transform, respectively, into χ N and χ N +1 for both positive and negative δ N for α → 0. This leads to appearance of a modulus of |δ N | and sign(δ N ) in Eq.…”

Section: A Isolated Ring Adiabatic Radiation Switchingmentioning

confidence: 99%

Resonant inverse Faraday effect in nanorings

Koshelev

Kachorovskii

Titov³

2015

Phys. Rev. B

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A circularly polarized light can induce a dissipationless dc current in a quantum nanoring which is responsible for a resonant helicity-driven contribution to magnetic moment. This current is not suppressed by thermal averaging despite its quantum nature. We refer to this phenomenon as quantum resonant inverse Faraday effect. For weak electromagnetic field, when the characteristic coupling energy is small compared to the energy level spacing, we predict narrow resonances in the circulating current and, consequently, in the magnetic moment of the ring. For strong fields, the resonances merge into a wide peak with a width determined by the spectral curvature. We further demonstrate that weak short-range disorder split the resonances and induce additional particularly sharp and high resonant peaks in dc current and magnetization. In contrast, long-range disorder leads to a chaotic behavior of the system in a vicinity of the separatrix that divides the phase space of the system into the regions with dynamically localized and delocalized states.

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Use of the Faraday optical transformer for ultrafast magnetization reversal of nanomagnets

Cited by 16 publications

References 27 publications

Coherent π-electron dynamics of (P)-2,2′-biphenol induced by ultrashort linearly polarized UV pulses: Angular momentum and ring current

Coherent π-electron dynamics of (P)-2,2′-biphenol induced by ultrashort linearly polarized UV pulses: Angular momentum and ring current

Quantum Control of Coherent π-Electron Dynamics in Aromatic Ring Molecules

Resonant inverse Faraday effect in nanorings

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