Orbital-resolved spin model for thermal magnetization switching in rare-earth-based ferrimagnets

Wienholdt, Sönke; Hinzke, Denise; Carva, Karel; Oppeneer, Peter M.; Nowak, Ulrich

doi:10.1103/physrevb.88.020406

Cited by 122 publications

(137 citation statements)

References 30 publications

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“…The element-selective technique allowed us moreover to observe the element-specific dynamics of the so-called "all-optical switching" (AOS) [8] in GdFeCo alloys, finding that it unexpectedly proceeds through a transient ferromagneticlike state where the FeCo sublattice magnetization points in the same direction as that of the Gd sublattice before complete reversal [5,9]. Recent theoretical works supported the distinct demagnetization times observed experimentally [10][11][12] and their crucial role on the transient ferromagneticlike state. AOS has been also demonstrated for other rare-earth transition-metal ferrimagnetic alloys as TbFe [13], TbCo [14], TbFeCo [15], DyCo [16], HoFeCo [16], synthetic ferrimagnets [16][17][18], and very recently in the hard-magnetic ferromagnet FePt [19].…”

Section: Introductionmentioning

confidence: 90%

“…Although the full theoretical explanation of the thermally driven AOS process is still a topic of debate [9,12,[20][21][22][23], the distinct demagnetization rates of each of the constituting elements has been suggested as the main driving mechanism * denise.hinzke@uni-konstanz.de for the AOS observed on antiferromagnetically coupled alloy [9,10,12]. These findings have highlighted the question how ultrafast demagnetization would proceed in ferromagnetically coupled two-sublattice materials such as permalloy (Py).…”

Section: Introductionmentioning

confidence: 99%

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Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys

et al. 2015

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A hierarchical multiscale approach to model the magnetization dynamics of ferromagnetic random alloys is presented. First-principles calculations of the Heisenberg exchange integrals are linked to atomistic spin models based upon the stochastic Landau-Lifshitz-Gilbert (LLG) equation to calculate temperature-dependent parameters (e.g., effective exchange interactions, damping parameters). These parameters are subsequently used in the Landau-Lifshitz-Bloch (LLB) model for multisublattice magnets to calculate numerically and analytically the ultrafast demagnetization times. The developed multiscale method is applied here to FeNi (permalloy) as well as to copper-doped FeNi alloys. We find that after an ultrafast heat pulse the Ni sublattice demagnetizes faster than the Fe sublattice for the here-studied FeNi-based alloys.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys

et al. 2015

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“…Here each sublattice is separately coupled to the same heat bath, although they could be coupled to different heath baths, such as electron and phonon heat baths as shown in Ref. 28 or the same sublattice can be coupled simultaneously to the two baths. 29 As a consequence of the different magnetization response of each sublattice, given by the intrinsic parameters, one sublattice can heat faster ("hot") than the other ("cold").…”

Section: Theoretical Description Of Ultrafast Magnetization Dynammentioning

confidence: 99%

Controlling the polarity of the transient ferromagneticlike state in ferrimagnets

et al. 2014

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It was recently observed that the two antiferromagnetically coupled sublattices of a rare earth-transition metal ferrimagnet can temporarily align ferromagnetically during femtosecond laser heating, but always with the transition metal aligning in the rare earth direction. This behavior has been attributed to the slower magnetization dynamics of the rare earth sublattice. The aim of this work was to assess how the difference in the speed of the transition metal and rare earth dynamics affects the formation of the transient ferromagnetic-like state and consequently controls its formation. Our investigation was performed using extensive atomistic spin simulations and analytic micromagnetic theory of ferrimagnets, with analysis of a large area of parameter space such as initial temperature, Gd concentration and laser fluence. Surprisingly, we found that at high temperatures, close to the Curie point, the rare earth dynamics become faster than those of the transition metal. Subsequently we show that the transient state can be formed with the opposite polarity, where the rare earth aligns in the transition metal direction. Our findings shed light on the complex behavior of this class of ferrimagnetic materials and highlight an important feature which must be considered, or even exploited, if these materials are to be used in ultrafast magnetic devices.

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“…Despite the still ongoing debate on the mechanism of ultrafast demagnetization it has been shown that spin dynamics simulations within the Landau-Lifshitz-Gilbert, Landau-Lifshitz-Bloch, or Landau-Lifshitz-Baryakhtar formulations [26][27][28][29] can be used to describe ultrafast laser-induced demagnetization in alloys when a sufficiently large and fast dissipation of spin angular momentum is assumed.…”

Section: Introductionmentioning

confidence: 99%

Ab initioinvestigation of light-induced relativistic spin-flip effects in magneto-optics

et al. 2015

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Excitation of a metallic ferromagnet such as Ni with an intensive femtosecond laser pulse causes an ultrafast demagnetization within approximately 300 fs. It was proposed that the ultrafast demagnetization measured in femtosecond magneto-optical experiments could be due to relativistic light-induced processes. We perform an ab initio investigation of the influence of relativistic effects on the magneto-optical response of Ni. To this end, we develop, first, a response theory formulation of the additional appearing ultra-relativistic terms in the Foldy-Wouthuysen transformed Dirac Hamiltonian due to the electromagnetic field, and, second, compute the influence of relativistic light-induced spin-flip transitions on the magneto-optics. Our ab initio calculations of relativistic spin-flip optical excitations predict that these can give only a very small contribution (≤ 0.1%) to the laser-induced magnetization change in Ni.

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Orbital-resolved spin model for thermal magnetization switching in rare-earth-based ferrimagnets

Cited by 122 publications

References 30 publications

Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys

Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys

Controlling the polarity of the transient ferromagneticlike state in ferrimagnets

Ab initioinvestigation of light-induced relativistic spin-flip effects in magneto-optics

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