Exchange Frequency Electron Spin Resonance in Ferrites

Kaplan, Joseph; Kittel, C.

doi:10.1063/1.1699018

Cited by 86 publications

(49 citation statements)

References 2 publications

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“…The K-K exchange resonance is a magnetic excitation which occurs between two coupled magnetic sublattices in ferrimagnets with a frequency proportional to the exchange coupling constant [18]. The origin of this mode can be related to a canting of the two sublattices away from their mutual exchange interaction.…”

Section: (B)mentioning

confidence: 99%

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Optical Excitation of a Forbidden Magnetic Resonance Mode in a Doped Lutetium-Iron-Garnet Film via the Inverse Faraday Effect

et al. 2010

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The effective magnetic field induced by a femtosecond pulse of circularly polarized light, via the inverse Faraday effect, is shown to excite a magnetic-dipole forbidden exchange spin resonance in a lutetium iron garnet. An external magnetic field cannot excite this mode, as the iron sublattices have the same gyromagnetic ratio and no net torque can be applied between them. However, since the sublattices have different magneto-optical susceptibilities, the inverse Faraday effect induces different effective fields on different iron sites, allowing excitation.

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Section: (B)mentioning

confidence: 99%

“…Instead, the best that can be achieved is a comparison with theory. The equation for the resonance frequency is [18] …”

Section: Prl 105 107402 (2010) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Optical Excitation of a Forbidden Magnetic Resonance Mode in a Doped Lutetium-Iron-Garnet Film via the Inverse Faraday Effect

et al. 2010

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“…measurements reasonably well. Assuming the same parameters and a typical value of 1 ϫ 10 4 for ex , 14 Eq. ͑5͒ predicts the optical exchange mode with a minimum frequency of 980 MHz around the angular momentum compensation temperature T L .…”

Section: Figmentioning

confidence: 99%

Magnetization dynamics of the ferrimagnet CoGd near the compensation of magnetization and angular momentum

et al. 2006

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Magnetization dynamics in alloys of ferrimagnetic CoGd have been studied in the vicinity of the magnetization and angular momentum compensation point as a function of alloy composition and temperature. In agreement with standard mean-field treatments of the dynamics of the total magnetization we observe an increase of the precessional frequency and the effective damping parameter near the angular momentum compensation point. We demonstrate the consistency of the magnetization dynamics extracted from frequency domain methods such as ferromagnetic resonance and time resolved laser pump-probe measurements. DOI: 10.1103/PhysRevB.74.134404 PACS number͑s͒: 75.40.Gb, 75.50.Gg, 76.50.ϩg Transition metal ͑TM͒ rare earth ͑RE͒ ferrimagnets are ideal canonical systems to probe magnetization dynamics. Typically, TM-RE alloys are nearly amorphous materials. The TM sublattice is antiferromagnetically ͑AF͒ coupled to the RE sublattice. When the coupling is strong, as, e.g., in CoGd, there are two transition temperatures, the magnetization compensation temperature T M where M Gd = M Co , and the angular momentum compensation temperature T L , where M Gd / ␥ Gd = M Co / ␥ Gd , and ␥ is the gyromagnetic ratio. These temperatures are sensitive functions of the relative concentration. At the magnetic compensation temperature, applied magnetic fields cannot couple to the magnetization to alter its energy since M Gd − M Co = M eff = 0. Angular momentum is quenched at the angular momentum compensation point, where the AF coupled sublattices gyrate 180°out of phase about the magnetic field. Studying the dynamics in ferrimagnetic systems are complicated by these tightly coupled AF sublattices. As T L is approached from low temperatures, the phenomenological mean-field damping parameter ␣ eff which governs how fast the system as a whole dissipates energy increases quickly, and the gyromagnetic frequency changes sign as the angular momentum of the dominant sublattice changes from Gd to Co. An ideal ferrimagnet should dissipate angular momentum instantaneously at T L .1,2 CoGd was chosen for this study because T M and T L are very close to each other, and the intrinsic orbital moment of Gd is essentially zero, thereby eliminating additional loss channels due to spin-orbit coupling. 3 We compare experimental results obtained by a frequency domain method used to study the dynamics of the total magnetization of M eff -namely, ferromagnetic resonance ͑FMR͒-to time domain ultrafast laser pump/probe experiments.The most straight forward method to excite magnetization dynamics uses strong magnetic field pulses that couple directly to the magnetization ͑spin͒.4,5 These field pulses are typically produced by external sources. However, these methods cannot excite the magnetization at the magnetization compensation point in a ferrimagnet since there is no net magnetic moment one can couple to. Another method to excite spin-systems employs ultrashort laser pulses that alter the magnetic system by heating across a critical temperature ͑Curie, Néel, ...

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“…6,7,8,9,10 The microscopic nature of the magnetoelectric effects can be better understood through the studies of the optical excitations such as IR active electromagnons and lattice vibrations that are modified by the spin-lattice interaction. 11,12,13,14,15,16,17,18,19 Due to the coincidence of the temperatures for the FM ordering of Dy spins and the AFE lattice ordering in Dy-IG, we expected an interesting behavior for the low-frequency optical phonons, which are related to the displacements of the heaviest ions (Dy) and spin-related ligand field (LF) transitions and Kaplan-Kittel (KK) 20 magnetic exchange resonance modes in Dy-IG. The main results of this paper are (i) the observed correlation between the magnetic field-induced changes of magnetic susceptibility in Dy-IG is followed by the discussion of the experimental data.…”

Section: Introductionmentioning

confidence: 99%

Far-infrared spectra of the magnetic exchange resonances and optical phonons and their connection to magnetic and dielectric properties of Dy3Fe5O
Kang
¹
,
Standard
²
,
Rogers
³

et al. 2012
Phys. Rev. B
17
1
5
0
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Far-infrared spectra of ferrimagnetic Dy 3 Fe 5 O 12 single crystals have been studied in the spectral range between 12 and 700 cm -1 and in a wide temperature range between 5 K and 300 K using transmission spectroscopy and rotating analyzer ellipsometry. In the temperature range below T C =16 K for the magnetic ordering of Dy 3+ spins, a number of ligand field (LF) and Kaplan-Kittel (KK) exchange resonance modes have been found. Temperature dependences of their frequencies allowed us to estimate the ratio between the Fe−Dy and Dy−Dy exchange constants.We found that variation of the oscillator strength of the KK modes correlates with the magnetic field induced changes of magnetic permeability. The low temperature peak in the static value of the dielectric function at T C =16 K may be related to the observed temperature-induced variation of the oscillator strength of the optical phonons.

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Exchange Frequency Electron Spin Resonance in Ferrites

Cited by 86 publications

References 2 publications

Optical Excitation of a Forbidden Magnetic Resonance Mode in a Doped Lutetium-Iron-Garnet Film via the Inverse Faraday Effect

Optical Excitation of a Forbidden Magnetic Resonance Mode in a Doped Lutetium-Iron-Garnet Film via the Inverse Faraday Effect

Magnetization dynamics of the ferrimagnet CoGd near the compensation of magnetization and angular momentum

Far-infrared spectra of the magnetic exchange resonances and optical phonons and their connection to magnetic and dielectric properties of Dy3Fe5O
Kang
¹
,
Standard
²
,
Rogers
³

et al. 2012
Phys. Rev. B
17
1
5
0
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Exchange Frequency Electron Spin Resonance in Ferrites

Cited by 86 publications

References 2 publications

Optical Excitation of a Forbidden Magnetic Resonance Mode in a Doped Lutetium-Iron-Garnet Film via the Inverse Faraday Effect

Optical Excitation of a Forbidden Magnetic Resonance Mode in a Doped Lutetium-Iron-Garnet Film via the Inverse Faraday Effect

Magnetization dynamics of the ferrimagnet CoGd near the compensation of magnetization and angular momentum

Far-infrared spectra of the magnetic exchange resonances and optical phonons and their connection to magnetic and dielectric properties of Dy3Fe5OKang1, Standard2, Rogers3 et al. 2012Phys. Rev. B17150View full textAdd to dashboardCite

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Far-infrared spectra of the magnetic exchange resonances and optical phonons and their connection to magnetic and dielectric properties of Dy3Fe5O
Kang
¹
,
Standard
²
,
Rogers
³

et al. 2012
Phys. Rev. B
17
1
5
0
View full text Add to dashboard Cite