Manipulating magnetism by ultrafast control of the exchange interaction

Mentink, Johan H.

doi:10.1088/1361-648x/aa8abf

Cited by 80 publications

(75 citation statements)

References 99 publications

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“…We believe that the current results will pave the way for manipulating the intrinsic property of 2D insulating honeycomb magnets such as CrX 3 (X = Br, Cl, I), using circularlypolarized light. Furthermore, the predicted results are pertinent to new experiments and will remarkably impact future research in this field with potential practical applications to photo-magnonics [82], magnon spintronics [37,38], and ultrafast optical control of magnetic spin currents [36,[83][84][85].…”

Section: Discussionmentioning

confidence: 99%

Magnonic Floquet Hofstadter butterfly

Owerre

2018

Annals of Physics

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We introduce the magnonic Floquet Hofstadter butterfly in the two-dimensional insulating honeycomb ferromagnet. We show that when the insulating honeycomb ferromagnet is irradiated by an oscillating space-and time-dependent electric field, the hopping magnetic dipole moment (i.e. magnon quasiparticles) accumulate the Aharonov-Casher phase. In the case of only space-dependent electric field, we realize the magnonic Hofstadter spectrum with similar fractal structure as graphene subject to a perpendicular magnetic field, but with no spin degeneracy due to broken time-reversal symmetry by the ferromagnetic order. In addition, the magnonic Dirac points and Landau levels occur at finite energy as expected in a bosonic system. Remarkably, this discrepancy does not affect the topological invariant of the system. Consequently, the magnonic Chern number assumes odd values and the magnon Hall conductance gets quantized by odd integers. In the case of both space-and time-dependent electric field, the theoretical framework is studied by the Floquet formalism. We show that the magnonic Floquet Hofstadter spectrum emerges entirely from the oscillating space-and time-dependent electric field, which is in stark contrast to electronic Floquet Hofstadter spectrum, where irradiation by circularly polarized light and a perpendicular magnetic field are applied independently. We study the deformation of the fractal structure at different laser frequencies and amplitudes, and analyze the topological phase transitions associated with gap openings in the magnonic Floquet Hofstadter butterfly. arXiv:1809.09102v1 [cond-mat.str-el]

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Section: Discussionmentioning

confidence: 99%

Magnonic Floquet Hofstadter butterfly

Owerre

2018

Annals of Physics

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“…The theoretical formalism and the results are general, and can be applied to different magnetic insulators, including the recently observed Dirac magnons in 3D antiferromagnet Cu 3 TeO 6 53-55 . We envision that our results will greatly impact future research in magnonic topological systems, and extend the experimental search for magnonic WPs to a broader class of 3D quantum magnetic insulators, with potential practical applications to features such as photo-magnonics 56 , magnon spintronics 57,58 , and ultrafast optical control of magnetic spin currents [59][60][61][62] .…”

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confidence: 91%

Floquet Weyl Magnons in Three-Dimensional Quantum Magnets

Owerre

2018

Sci Rep

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In three-dimensional (3D) quantum magnets, magnonic Weyl points (WPs) featuring linear band crossing of two non-degenerate magnon branches can emerge in certain lattice geometry when time-reversal symmetry is broken macroscopically. Unfortunately, there are very limited 3D quantum magnets that host magnonic WPs, and they are yet to be observed experimentally because the intrinsic perturbative interactions that break time-reversal symmetry macroscopically can be very negligible. Here, we present an alternative means via photo-irradiation, in which magnonic WPs can emerge in 3D quantum magnets without relying on intrinsic perturbative interactions to break time-reversal symmetry. By utilizing the magnonic Floquet-Bloch theory, we put forward the general theory of magnonic Floquet WPs in 3D quantum magnets. We show that periodically driven 3D magnonic Dirac nodal-line (DNL) and 3D magnonic gapped trivial insulators can generate 3D magnonic Floquet WPs, which can be tuned by the incident circularly-polarized light. We demonstrate the existence of magnonic Floquet WPs by combining the study of the magnon dispersions, Berry curvatures, and the anomalous thermal Hall effect. The general theoretical formalism can be applied to different magnetic insulators, and thus extending the concept of magnonic WPs to a broader class of 3D magnetically ordered systems.

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“…Eqs. (17) and (18) not only allow us to obtain an effective description of the low energy stateŝ P ν 0 , but also enable us to keep track of the coupling between the low energy space (spin:P ν 0 ) and the space with the highest excited states (charge:P ν 2 ). Eqs.…”

Section: Generalized Time-dependent Canonical Transformationmentioning

confidence: 99%

“…Recently, the ultrafast control of J ex has received significant interest both in experiments with cold atoms as well as in condensed matter systems [1][2][3][4][5][6][7][8][9][10][11]. An appealing way to achieve a control of J ex is to use periodic driving with off-resonant pulses as was extensively investigated theoretically [12][13][14][15][16][17]. In particular, it was predicted theoretically [12,13] and recently confirmed experimentally [11] that by tuning the strength and frequency of the driving, J ex can be reduced, enhanced and even reverse sign in a reversible way.…”

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confidence: 99%

Optical control of competing exchange interactions and coherent spin-charge coupling in two-orbital Mott insulators

et al. 2019

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In order to have a better understanding of ultrafast electrical control of exchange interactions in multi-orbital systems, we study a two-orbital Hubbard model at half filling under the action of a time-periodic electric field. Using suitable projection operators and a generalized time-dependent canonical transformation, we derive an effective Hamiltonian which describes two different regimes. First, for a wide range of non-resonant frequencies, we find a change of the bilinear Heisenberg exchange J ex that is analogous to the single-orbital case. Moreover we demonstrate that also the additional biquadratic exchange interaction B ex can be enhanced, reduced and even change sign depending on the electric field. Second, for special driving frequencies, we demonstrate a novel spin-charge coupling phenomenon enabling coherent transfer between spin and charge degrees of freedom of doubly ionized states. These results are confirmed by an exact time-evolution of the full two-orbital Mott-Hubbard Hamiltonian. Contents arXiv:1803.03796v2 [cond-mat.str-el] 1 Feb 2019 SciPost Physics Submission A Projection operators 19 B Effective Hamiltonian 20 C Spin-one and pseudo spin-one operators 22 D Derivation of the effective spin-one Hamiltonian 23 E Effective Hamiltonian with Spin-Charge coupling 27 References 28

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Manipulating magnetism by ultrafast control of the exchange interaction

Cited by 80 publications

References 99 publications

Magnonic Floquet Hofstadter butterfly

Magnonic Floquet Hofstadter butterfly

Floquet Weyl Magnons in Three-Dimensional Quantum Magnets

Optical control of competing exchange interactions and coherent spin-charge coupling in two-orbital Mott insulators

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