Dynamics of domain walls in bismuth-ytterbium-containing garnet ferrite films in the vicinity of the angular momentum compensation point

Randoshkin, V. V.; Polezhaev, V. A.; Sysoev, N. N.; Sazhin, Yu. N.

doi:10.1134/1.1562240

Cited by 13 publications

(9 citation statements)

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“…As shown above, in a ferrimagnet close to the compensation point both the frequency of the magnetization precession ͑Stanciu et al, 2006͒ and the domain wall velocity ͑Weng and Kryder, 1993; Randoshkin et al, 2003͒ strongly increase due to the divergence of the gyromagnetic ratio ͑see Sec. IV.E.4͒.…”

Section: G Magnetization Reversalmentioning

confidence: 99%

Ultrafast optical manipulation of magnetic order

2010

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The interaction of subpicosecond laser pulses with magnetically ordered materials has developed into a fascinating research topic in modern magnetism. From the discovery of subpicosecond demagnetization over a decade ago to the recent demonstration of magnetization reversal by a single 40 fs laser pulse, the manipulation of magnetic order by ultrashort laser pulses has become a fundamentally challenging topic with a potentially high impact for future spintronics, data storage and manipulation, and quantum computation. Understanding the underlying mechanisms implies understanding the interaction of photons with charges, spins, and lattice, and the angular momentum transfer between them. This paper will review the progress in this field of laser manipulation of magnetic order in a systematic way. Starting with a historical introduction, the interaction of light with magnetically ordered matter is discussed. By investigating metals, semiconductors, and dielectrics, the roles of ͑nearly͒ free electrons, charge redistributions, and spin-orbit and spin-lattice interactions can partly be separated, and effects due to heating can be distinguished from those that are not. It will be shown that there is a fundamental distinction between processes that involve the actual absorption of photons and those that do not. It turns out that for the latter, the polarization of light plays an essential role in the manipulation of the magnetic moments at the femtosecond time scale. Thus, circularly and linearly polarized pulses are shown to act as strong transient magnetic field pulses originating from the nonabsorptive inverse Faraday and inverse Cotton-Mouton effects, respectively. The recent progress in the understanding of magneto-optical effects on the femtosecond time scale together with the mentioned inverse, optomagnetic effects promises a bright future for this field of ultrafast optical manipulation of magnetic order or femtomagnetism.

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Section: G Magnetization Reversalmentioning

confidence: 99%

Ultrafast optical manipulation of magnetic order

2010

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“…The speed of the latter process, naturally, depends on the mobility of the domain walls, which in GeFeCo alloys is strongly temperature dependent. [62][63][64] Moreover, the speed is very high in the vicinity of the angular momentum compensation temperature T A . When a sample being below T A is subjected to a circularly polarized laser pulse, the laser excited area always contains domains brought close to T A where the domain wall mobility is the largest.…”

Section: Speed Of the All-optical Reversal In Gdfeco Alloysmentioning

confidence: 99%

All-optical magnetization reversal by circularly polarized laser pulses: Experiment and multiscale modeling

et al. 2012

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We present results of detailed experimental and theoretical studies of all-optical magnetization reversal by single circularly-polarized laser pulses in ferrimagnetic rare earth-transition metal (RE-TM) alloys Gd x Fe 90−x Co 10 (20% < x < 28%). Using single-shot time-resolved magneto-optical microscopy and multiscale simulations, we identified and described the unconventional path followed by the magnetization during the reversal process. This reversal does not involve precessional motion of magnetization but is governed by the longitudinal relaxation and thus has a linear character. We demonstrate that this all-optically driven linear reversal can be modeled as a result of a two-fold impact of the laser pulse on the medium. First, due to absorption of the light and ultrafast laser-induced heating, the medium is brought to a highly nonequilibrium state. Simultaneously, due to the ultrafast inverse Faraday effect the circularly polarized laser pulse acts as an effective magnetic field of the amplitude up to ∼20 T. We show that the polarization-dependent reversal triggered by the circularly polarized light is feasible only in a narrow range (below 10%) of laser fluences. The duration of the laser pulse required for the reversal can be varied from ∼40 fs up to at least ∼1700 fs. We also investigate experimentally the role of the ferrimagnetic properties of GdFeCo in the all-optical reversal. In particular, the optimal conditions for the all-optical reversal are achieved just below the ferrimagnetic compensation temperature, where the magnetic information can be all-optically written by a laser pulse of minimal fluence and read out within just 30 ps. We argue that this is the fastest write-read event demonstrated for magnetic recording so far.

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“…At T A , application of a magnetic field should instantaneously flip the magnetization. The reason for this is that at T A , both the frequency of the magnetization precession [11] and the domain-wall velocity [15,16] increase strongly due to the divergence of the gyromagnetic ratio [17]. In other words, at T A , magnetization can be regarded as a mechanical system with no inertia which can be moved by the slightest torque.…”

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“…Because the effective gyromagnetic ratio of the ferrimagnetic system eff is inversely proportional to the total angular momentum of the system ( eff M=A), theoretically eff diverges when T A (A 0) is reached [17]. Both magnetization precession frequency [11] and domain-wall velocity [15,16] are proportional to this effective gyromagnetic ratio. Thus, in the vicinity of T A , a many fold increase of the frequency of the spin precession and domain-wall velocity are expected.…”

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Subpicosecond Magnetization Reversal across Ferrimagnetic Compensation Points

et al. 2007

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Subpicosecond magnetization reversal is experimentally demonstrated by ultrafast heating of a ferrimagnet across its compensation points, under an applied magnetic field. While the reversal is initiated by crossing the magnetization compensation temperature, the short reversal time is related to the angular momentum compensation, where the dynamics of the system is highly accelerated owing to the divergence of the gyromagnetic ratio. These results demonstrate the feasibility of subpicosecond magnetization reversal previously believed impossible.

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Dynamics of domain walls in bismuth-ytterbium-containing garnet ferrite films in the vicinity of the angular momentum compensation point

Cited by 13 publications

References 0 publications

Ultrafast optical manipulation of magnetic order

Ultrafast optical manipulation of magnetic order

All-optical magnetization reversal by circularly polarized laser pulses: Experiment and multiscale modeling

Subpicosecond Magnetization Reversal across Ferrimagnetic Compensation Points

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