Ultrafast relaxation rates and reversal time in disordered ferrimagnets

Suarez, O. J.; Nieves, P.; Laroze, David; Altbir, D.; Chubykalo‐Fesenko, O.

doi:10.1103/physrevb.92.144425

Cited by 14 publications

(15 citation statements)

References 17 publications

(28 reference statements)

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“…The observed fluence independency of the demagnetization time can be understood within the model put forward by Suarez et al 50 and Atxitia et al 51 . Their model predicts only a week fluence dependence of the demagnetization time as long as the system is not heated above the Curie temperature, which is true in our case, as discussed above.…”

Section: Discussionmentioning

confidence: 71%

Single-shot time-resolved magnetic x-ray absorption at a free-electron laser

et al. 2019

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Ultrafast dynamics are generally investigated using stroboscopic pump-probe measurements, which characterize the sample properties for a single, specific time delay. These measurements are then repeated for a series of discrete time delays to reconstruct the overall time trace of the process. As a consequence, this approach is limited to the investigation of fully reversible phenomena. We recently introduced an off-axis zone plate based X-ray streaking technique, which overcomes this limitation by sampling the relaxation dynamics with a single femtosecond X-ray pulse streaked over a picosecond long time window. In this article we show that the X-ray absorption cross section can be employed as the contrast mechanism in this novel technique. We show that changes of the absorption cross section on the percent level can be resolved with this method. To this end we measure the ultrafast magnetization dynamics in CoDy alloy films. Investigating different chemical compositions and infrared pump fluences, we demonstrate the routine applicability of this technique. Probing in transmission the average magnetization dynamics of the entire film, our experimental findings indicate that the demagnetization time is independent of the specific infrared laser pump fluence. These results pave the way for the investigation of irreversible phenomena in a wide variety of scientific areas.

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Section: Discussionmentioning

confidence: 71%

Single-shot time-resolved magnetic x-ray absorption at a free-electron laser

et al. 2019

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“…We show in this work that the conclusions extracted from FeCoGd alloys cannot be extended to our RE-TM alloys. It is worth noting that in FeCoGd alloys, experimental [7,[20][21][22][23] and theoretical [40,41,[60][61][62][63] results demonstrate that in addition to the laser induced demagnetization a particular Helicity-Independent All-Optical Switching (HI-AOS) of the spins is possible [64]. We note that the HI-AOS is observed only if the sample temperature is in the proximity of T comp [65].…”

Section: Discussionmentioning

confidence: 74%

“…Several other theoretical models such as the LLB model [39,40,60] and the microscopic 3 temperature model (m3TM) [3,62] have related τ to microscopic magnetic properties of ferrimagnets. These models predict that the macroscopic parameter T comp , has no influence on τ in line with our results.…”

Section: Discussionmentioning

confidence: 99%

Element-resolved ultrafast demagnetization rates in ferrimagnetic CoDy

et al. 2017

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Femtosecond laser induced ultrafast magnetization dynamics have been studied in multisublattice CoxDy1-x alloys. By performing element and time-resolved X-ray spectroscopy, we distinguish the ultrafast quenching of Co3d and Dy4f magnetic order when the initial temperatures are below (T=150K) or above (T=270K) the temperature of magnetic compensation (Tcomp). In accordance with former element-resolved investigations and theoretical calculations, we observe different dynamics for Co3d and Dy4f spins. In addition we observe that, for a given laser fluence, the demagnetization amplitudes and demagnetization times are not affected by the existence of a temperature of magnetic compensation. However, our experiment reveals a twofold increase of the ultrafast demagnetization rates for the Dy sublattice at low temperature. In parallel, we measure a constant demagnetization rate of the Co3d sublattice above and below Tcomp. This intriguing difference between the Dy4f and Co3d sublattices calls for further theoretical and experimental investigations.Comment: 6 Figure, 2 Table

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“…However, in weakly coupled ferrimagnets, only the material with the largest exchange value slows down at the common Curie temperature [35].…”

Section: The Classical Two-sublattice Landau-lifshitz-bloch Equation mentioning

confidence: 99%

The classical two-sublattice Landau–Lifshitz–Bloch equation for all temperatures

Nieves

Atxitia

Chantrell

et al. 2015

Low Temperature Physics

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Micromagnetic modeling has proved itself as a widely used tool, complimentary in many respects to experimental measurements. The Landau-Lifshitz equation provides a basis for this modeling, especially where the dynamical behaviour is concerned. However, this approach is strictly valid only for zero temperature and for high temperatures must be replaced by a more thermodynamically consistent approach such as the the LandauLifshitz-Bloch (LLB) equation. Here we review the recently derived LLB equation for two-sublattice systems and extend its derivation for temperatures above the Curie temperature. We present comparison with many-body atomistic simulations and show that this equation can describe the ultra-fast switching in ferrimagnets, observed experimentally.PACS: 75.10.Hk Classical spin models; 75.Magnetic properties and materials; 75.78.-n Magnetization dynamics.

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Ultrafast relaxation rates and reversal time in disordered ferrimagnets

Cited by 14 publications

References 17 publications

Single-shot time-resolved magnetic x-ray absorption at a free-electron laser

Single-shot time-resolved magnetic x-ray absorption at a free-electron laser

Element-resolved ultrafast demagnetization rates in ferrimagnetic CoDy

The classical two-sublattice Landau–Lifshitz–Bloch equation for all temperatures

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