Unifying ultrafast demagnetization and intrinsic Gilbert damping in Co/Ni bilayers with electronic relaxation near the Fermi surface

Zhang, Wei; He, Wei; Zhang, Xiang-Qun; Cheng, Zhao‐Hua; Teng, Jun; Fähnle, M.

doi:10.1103/physrevb.96.220415

Cited by 34 publications

(23 citation statements)

References 60 publications

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“…Since the discovery of ultrafast magnetization dynamics 18 , intense research efforts have been made to reveal the underlying mechanism driving the ultrafast demagnetization 6,7,29,[32][33][34][35][36][37][38][39][40][41][42][43] . While these studies report overall very similar magnetization dynamics, one notices differences in details such as the specific characteristic time scale of magnetization quenching and partial recovery.…”

Section: Discussionmentioning

confidence: 99%

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: 99%

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

et al. 2019

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“…H q =  The red solid lines are the fitting lines and the details of fitting procedure are given in SM. The fitting equation is from previously published [33,34].…”

Section: Resultsmentioning

confidence: 99%

Femtosecond laser-heating effect on the magnetization dynamics in perpendicularly magnetized Ta/CoFeB/MgO film

et al. 2019

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We have studied the effect of ultrafast laser-heating on the magnetization dynamics of perpendicularly magnetized CoFeB film by means of the time-resolved magneto-optical Kerr rotation effect. The effective perpendicular magnetic anisotropy field H K is significantly decreased with enhancing the pump laser-fluence in a moderate range of 5-12 mJ cm −2 . The Gilbert damping, however, is found to be independent of the pump fluence. These findings provide a new method of separately manipulating the Gilbert damping and perpendicular magnetic anisotropy.

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“…The intrinsic one is related to the electronic band structure near the Fermi level. Since the extrinsic one is caused by microstructural inhomogeneity and depends on the magnitude of the external magnetic field, the linear dependence can be obtained only when the extrinsic one is almost suppressed under strong external magnetic fields 34 . In the following, we will focus on the intrinsic one α 0 .…”

Section: Resultsmentioning

confidence: 99%

Tuning of the intrinsic magnetic damping parameter in epitaxial CoNi(001) films : Role of the band-filling effect

Shi

Hou

et al. 2019

Phys. Rev. B

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Band filling effect, which is due to tuning the electron occupation number near the Fermi level, on the intrinsic magnetic damping parameter is demonstrated by employing high quality epitaxial Co1−xNix alloy films, in which the Fermi level and the density of states can be continuously tuned by varying the Ni concentration x. The intrinsic magnetic damping parameter, measured by timeresolved magneto-optical Kerr effect, changes weakly at small x and increases sharply for x > 0.80. The experimental results are well reproduced by the density functional theory calculation. More interestingly, the magnetic damping parameter and the density of states near the Fermi level share similar variation trends, demonstrating their correlation. The band filling effect in 3d magnetic transition metal alloys provides a way to tune the magnetic damping parameter as a key element in controlling of energy loss and speed of spintronic devices.

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Unifying ultrafast demagnetization and intrinsic Gilbert damping in Co/Ni bilayers with electronic relaxation near the Fermi surface

Abstract: The ability to controllably manipulate the laser-induced ultrafast magnetic dynamics is a prerequisite for future high speed spintronic devices.

Cited by 34 publications

References 60 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

Femtosecond laser-heating effect on the magnetization dynamics in perpendicularly magnetized Ta/CoFeB/MgO film

Tuning of the intrinsic magnetic damping parameter in epitaxial CoNi(001) films : Role of the band-filling effect

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