Magnetomechanical coupling and ferromagnetic resonance in magnetic nanoparticles

Keshtgar, Hedyeh; Streib, Simon; Kamra, Akashdeep; Blanter, Yaroslav M.; Bauer, G.

doi:10.1103/physrevb.95.134447

Cited by 32 publications

(29 citation statements)

References 53 publications

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“…In condensed matter systems, exchange of angular momentum between electrons' spins and a crystal lattice governs the Einstein-de Haas 2 and Barnett 3 effects. These effects play a key role in magnetoelasticity 4 , in the physics of molecular and atomic magnets [5][6][7][8] , nano-magneto-mechanical systems [9][10][11][12][13] , spintronics [14][15][16] , and ultrafast magnetism [17][18][19][20] .…”

Section: Introductionmentioning

confidence: 99%

Quantum many-body dynamics of the Einstein–de Haas effect

Mentink¹,

Katsnelson²,

Lemeshko

2019

Phys. Rev. B

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In 1915, Einstein and de Haas and Barnett demonstrated that changing the magnetization of a magnetic material results in mechanical rotation, and vice versa. At the microscopic level, this effect governs the transfer between electron spin and orbital angular momentum, and lattice degrees of freedom, understanding which is key for molecular magnets, nano-magneto-mechanics, spintronics, and ultrafast magnetism. Until now, the timescales of electron-to-lattice angular momentum transfer remain unclear, since modeling this process on a microscopic level requires addition of an infinite amount of quantum angular momenta. We show that this problem can be solved by reformulating it in terms of the recently discovered angulon quasiparticles, which results in a rotationally invariant quantum many-body theory. In particular, we demonstrate that non-perturbative effects take place even if the electron-phonon coupling is weak and give rise to angular momentum transfer on femtosecond timescales. J λl − ω k ω + iε + ∆E JM J λl − ω k (C9) K2 M J λl (ω) = k |U λ (k) Q λl | 2 ∆E JM 0 J λl − ω k 2 ω + iε + ∆E JM J λl − ω k (C10) with ∆E JM J = E − E JM J and ∆E JM J λl = E − E JM J λl , where E is the variational ground-state energy. The integrals are computed numerically with ε 1 until convergence is achieved. Explicit expressions for the energy of the bare impurity, E JM J , and the energy of the bare impurity with phonons excited, E JM J λl , as well as for Q λl , are given in Appendix B.

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Section: Introductionmentioning

confidence: 99%

Quantum many-body dynamics of the Einstein–de Haas effect

Mentink¹,

Katsnelson²,

Lemeshko

2019

Phys. Rev. B

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“…where α(> 0) is the LL damping parameter, −ω/γ is the so-called Barnett field originating from the particle rotation (see, e.g., Ref. 26 ), and H eff is the effective magnetic field acting on M. In particular, in the case of uniaxial particles the effective magnetic field is given by…”

Section: Basic Equations For Coupled Magneto-mechanical Dynamicsmentioning

confidence: 99%

Dissipation-induced rotation of suspended ferromagnetic nanoparticles

2019

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We report the precessional rotation of magnetically isotropic ferromagnetic nanoparticles in a viscous liquid that are subjected to a rotating magnetic field. In contrast to magnetically anisotropic nanoparticles, the rotation of which occurs due to coupling between the magnetic and lattice subsystems through magnetocrystalline anisotropy, the rotation of isotropic nanoparticles is induced only by magnetic dissipation processes. We propose a theory of this phenomenon based on a set of equations describing the deterministic magnetic and rotational dynamics of such particles. Neglecting inertial effects, we solve these equations analytically, find the magnetization and particle precessions in the steady state, determine the components of the particle angular velocity and analyze their dependence on the model parameters. The possibility of experimental observation of this phenomenon is also discussed.

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“…There, the power loss was obtained on the basis of the Lagrangian equation in the noise-free and single-particle approximation. After this, the progress in the description of the energy dissipation of a viscously coupled nanoparticle with finite anisotropy driven by an alternating field was achieved in [25,26,27]. The further development of this model assumes the accounting of thermal noise firstly.…”

Section: Introductionmentioning

confidence: 99%

Uniform and nonuniform precession of a nanoparticle with finite anisotropy in a liquid: Opportunities and limitations for magnetic fluid hyperthermia

Lyutyy

Hryshko

Yakovenko

2019

Journal of Magnetism and Magnetic Materials

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We focus on an in-depth study of the forced dynamics of a ferromagnetic single-domain uniaxial nanoparticle placed in a viscous fluid and driven by an external rotating magnetic field. The process of conversion of magnetic and mechanical energies into heat is a physical basis for magnetic fluid hyperthermia that is very promising for cancer treatment. The dynamical approximation allows us to establish the limits of the heating rate and understand the logic of selection of the system parameters to optimize the therapy. Based on the developed analytical and numerical tools, we analyze from a single viewpoint the synchronous and asynchronous rotation of the nanoparticle or/and its magnetization in the following three cases. For the beginning, we actualize the features of the internal magnetic dynamics, when the nanoparticle body is supposed to be fixed. Then, we study the rotation of the whole nanoparticle, when its magnetization is supposed to be locked to the crystal lattice. And, finally, we realize the analysis of the coupled motion, when the internal magnetic dynamics is performed in the rotated nanoparticle body. In all these cases, we describe analytically the uniform mode, or synchronous rotation along with an external field, while the nonuniform mode, or asynchronous rotation, is investigated numerically.

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Magnetomechanical coupling and ferromagnetic resonance in magnetic nanoparticles

Cited by 32 publications

References 53 publications

Quantum many-body dynamics of the Einstein–de Haas effect

Quantum many-body dynamics of the Einstein–de Haas effect

Dissipation-induced rotation of suspended ferromagnetic nanoparticles

Uniform and nonuniform precession of a nanoparticle with finite anisotropy in a liquid: Opportunities and limitations for magnetic fluid hyperthermia

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