Interplay of heating and helicity in all-optical magnetization switching

Alebrand, Sabine; Hassdenteufel, Alexander; Steil, Daniel; Cinchetti, Mirko; Aeschlimann, Martin

doi:10.1103/physrevb.85.092401

Cited by 62 publications

(54 citation statements)

References 32 publications

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“…The fact that the value of F min for pulse trains is above the value for unshaped pulses is understandable in terms of heat related effects. As it was shown in 8 a certain amount of heating is needed to obtain AOS. If in the case of a pulse train the irradiated sample area is already slightly cooled down between the single pulses, the total fluence of the pulse train must be higher compared to F min of the unshaped pulse to deliver the needed amount of heating.…”

Section: Discussionsupporting

confidence: 68%

“…The reason is that the heating due to the pulses following the x th pulse must be low enough to not exceed the thermal demagnetization threshold. Furthermore, it was shown in 8 that two pulses following each other with a delay of a few picoseconds both contribute to the switching. In the following we therefore assume that all pulses influence the switching process.…”

Section: Discussionmentioning

confidence: 99%

“…We point out that for both models (i) and (ii) heating is crucial for switching. Experimentally this has been confirmed by measurements of Alebrand et al 8. In these experiments the exciting laser pulses (coming with a certain repetition rate) were split into two pulses, one circularly (delivering helicity and heat) and one linearly polarized pulse (delivering just heat).…”

Section: Introductionmentioning

confidence: 99%

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All‐optical magnetization switching using phase shaped ultrashort laser pulses

Alebrand

Hassdenteufel

Steil

et al. 2012

Physica Status Solidi (a)

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Switching the magnetization without any external applied magnetic field by using ultrashort circularly polarized laser pulses is a fascinating and challenging topic of modern magnetism. Up to now there is still no consensus about the microscopic mechanism of this so called all‐optical switching (AOS) and several different models are suggested. In particular the importance of heat and helicity driven effects is still under discussion. In our experiment we varied the input of heating during the AOS process by utilizing pulse trains, created with a phase pulse shaper, to switch the magnetization. We show that AOS is possible with pulse trains having a temporal delay between the single pulses of more than a picosecond. The minimum switching fluence for pulse trains is found to be higher compared to switching with unshaped pulses. We mainly attribute this behavior to heat loss effects. Further we find that the minimum switching fluence depends on the number of pulses within a pulse train. We discuss our observations in terms of the currently debated theoretical models of AOS.

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Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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All‐optical magnetization switching using phase shaped ultrashort laser pulses

Alebrand

Hassdenteufel

Steil

et al. 2012

Physica Status Solidi (a)

Self Cite

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“…This observation lead to a debate as to the origin of the ultrafast switching [7,8]. The inverse Faraday effect (IFE) was originally proposed as the key driving mechanism for the reversal [6,9,10]. A further complication to the debate on all-optical switching (AOS) was presented in 2012 by Ostler et al where single 50 fs laser pulses were shown to drive deterministic magnetization reversal for both left, right, and linearly polarized light [11].…”

Section: Introductionmentioning

confidence: 99%

Conditions for thermally induced all-optical switching in ferrimagnetic alloys: Modeling of TbCo

et al. 2017

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“…11,[31][32][33][34][35][36] Recently we showed that a minimum amount of laser energy input of the order of the energy gap between the two ferrimagnetic modes, i.e.h∆ω ∼hω ex ∼ J RT (M FeCo (T 0 ) − M Gd (T 0 )), is required for the formation of the TFLS, 11 where ω ex is the frequency of the so-called antiferromagnetic coherent exchange mode. The disordered nature of the GdFeCo spin lattice leads an effect that the most efficient energy transfer (the smallest energy gap) does not correspond exactly to the coherent mode with k = 0 but to non-zero k value, related to the characteristic length of the Gd spins cluster size.…”

Section: B Formation Of the Transient Ferromagnetic Like Statementioning

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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Interplay of heating and helicity in all-optical magnetization switching

Cited by 62 publications

References 32 publications

All‐optical magnetization switching using phase shaped ultrashort laser pulses

All‐optical magnetization switching using phase shaped ultrashort laser pulses

Conditions for thermally induced all-optical switching in ferrimagnetic alloys: Modeling of TbCo

Controlling the polarity of the transient ferromagneticlike state in ferrimagnets

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