Spin-system radio-frequency superradiation: A phenomenological study and comparison with numeric simulations

Davis, C. L.; Henner, V. K.; Tchernatinsky, Alexander; Kaganov, I. V.

doi:10.1103/physrevb.72.054406

Cited by 14 publications

(7 citation statements)

References 17 publications

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“…[12,40], for a detailed recent work see Ref. [41]. At very low temperatures this effect can be even stronger than the homogeneous broadening mechanism caused by elastic collisions with the phonons.…”

Section: Resultsmentioning

confidence: 99%

Microwave emission from a crystal of molecular magnets: The role of a resonant cavity

2005

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We discuss the effects caused by a resonant cavity around a sample of a magnetic molecular crystal (such as Mn12-Ac), when a time dependent external magnetic field is applied parallel to the easy axis of the crystal. We show that the back action of the cavity field on the sample significantly increases the possibility of microwave emission. This radiation process can be supperradiance or a maserlike effect, depending on the strength of the dephasing. Our model provides further insight to the theoretical understanding of the bursts of electromagnetic radiation observed in recent experiments accompanying the resonant quantum tunneling of magnetization. The experimental findings up to now can all be explained as being a maser effect rather than superradiance. The results of our theory scale similarly to the experimental findings, i.e., with increasing sweep rate of the external magnetic field, the emission peaks are shifted towards higher field values.

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Section: Resultsmentioning

confidence: 99%

Microwave emission from a crystal of molecular magnets: The role of a resonant cavity

2005

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“…When placed into the high-field NMR magnet-without radio-frequency (rf) excitation-the system spontaneously emits a series of rf bursts instead of one, as expected from the usual theory of RD. [9,24,25] We show that this induces inhomogeneous spatial organization of the 129 Xe magnetization. Even if it appears possible to reproduce one emission leading to inhomogeneous spatial magnetization by numerical simulations, a series seems to be impossible to obtain in the framework of a classical dipolar field.…”

Section: Introductionmentioning

confidence: 98%

Observation of Noise‐Triggered Chaotic Emissions in an NMR‐Maser

et al. 2008

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We report a new phenomenon observed when the magnetization of dissolved hyperpolarized (129)Xe is intense and opposite to the Boltzmann magnetization. Without radio-frequency (rf) excitation, the system spontaneously emits a series of rf bursts characterized by very narrow bandwidths (0.03 Hz at 138 MHz). This chaotic NMR-maser illustrates the increase in the complexity of spin dynamics at high magnetization levels by unveiling an inhomogeneous spatial organization of the xenon magnetization and an apparent dependence of the xenon transverse relaxation time on its polarization and/or on time.

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“…Under these conditions, the radiative scattering rate increases to ⌫ SR = N⌫ through super-radiant emission. [22][23][24][25][26][27] We will develop this idea when calculating microwave emission spectra in the following paper. 28 The diagonalization of Eq.…”

Section: ͑25͒mentioning

confidence: 99%

Electrically induced spin resonance fluorescence. I. Theory

Nogaret¹,

Peeters²

2007

Phys. Rev. B

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We calculate the fluorescence of electron spins confined to a plane and driven into resonance by a magnetic field gradient and a constant magnetic field applied at right angles to each other. We solve the equation of motion of two-dimensional electrons in the magnetic field gradient to derive the dispersion curve of spin oscillators, the amplitude of electron oscillations, the effective magnetic field sensed by the electron spin, and the rate at which electrons are injected from an electrode into spin oscillators. We then switch on the interaction between the spin magnetic dipole and the electromagnetic field to find the fluorescence power radiated by the individual spin oscillators. The rate of radiative decay is first derived, followed by the probability of sequential photon emission whereby a series of spontaneous decays occurs at random times separated by intervals during which the spin performs Rabi oscillations. The quantum correlations between random radiative decays manifest as bursts of emission at regular intervals along the wire. We integrate all multiphoton processes to obtain an exact analytical expression for the radiated electromagnetic power. The present theory obtains all parameters of the problem including magnetodipole coupling, the particle dwell time in the magnetic field gradient, and the spin polarization of the incoming current. The output power contains a fine structure arising from the anharmonicity of electron oscillations and from nonlinear optical effects which both give satellite emission peaks at odd multiples of the fundamental frequency.

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Spin-system radio-frequency superradiation: A phenomenological study and comparison with numeric simulations

Cited by 14 publications

References 17 publications

Microwave emission from a crystal of molecular magnets: The role of a resonant cavity

Microwave emission from a crystal of molecular magnets: The role of a resonant cavity

Observation of Noise‐Triggered Chaotic Emissions in an NMR‐Maser

Electrically induced spin resonance fluorescence. I. Theory

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