Ultrafast spin-switching of a ferrimagnetic alloy at room temperature traced by resonant magneto-optical Kerr effect using a seeded free electron laser

Taguchi, M.; Someya, T.; Kubota, Yuya; Ito, Suguru; Wadati, H.; Fujisawa, Masami; Capotondi, Flavio; Pedersoli, Emanuele; Manfredda, Michele; Raimondi, Lorenzo; Кискинова, М.; Fujii, Jun; Moras, Paolo; Tsuyama, T.; Nakamura, Tetsuya; Kato, Takeshi; Higashide, T.; Iwata, S.; Yamamoto, Shûji; Shin, Sung‐Chul; Matsuda, Iwao

doi:10.1063/1.4927828

Cited by 22 publications

(15 citation statements)

References 28 publications

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“…The magnetic properties of many amorphous building blocks can, on the other hand, be tuned almost continuously through their composition. [ 17,20 ] The sputter process allows industrial‐scale production of amorphous multilayers with smooth interfaces, while recent advances in additive manufacturing of amorphous Fe‐based materials open up new perspectives to create amorphous composite magnets of larger sizes and different shapes. [ 21,22 ]…”

Section: Introductionmentioning

confidence: 99%

Rigid Exchange Coupling in Rare‐Earth‐Lean Amorphous Hard/Soft Nanocomposites

Rani

Muscas

Stopfel

et al. 2020

Adv Elect Materials

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considerably larger than for a single hard phase, since the strong coercivity H c of the hard phase is combined with the high saturation magnetization M s of the soft phase. [7] With sufficiently strong exchange coupling between the two magnetic phases, the soft phase moments will follow the hard phase during magnetization reversal. Such a rigidly exchange-coupled composite exhibits a magnetic hysteresis loop characteristic of a single ferromagnetic phase, [8] rather than a loop with drops, kinks, or shoulders from two superposed switching processes. [9] For most practical applications, it is also crucial that the Curie temperature T c of the composite material is well above room temperature, and that the overall M s value is large. A model for the interfacial exchangespring coupling between a soft and a hard phase was introduced by Goto et al. [10] According to that model, the two phases can reverse their moments coherently, that is, as a single component, only if the coupling is strong enough to extend from the interface through the entire thickness of the soft phase. Thus, for a given combination of soft and hard materials, rigid coupling is only possible up to a critical thickness of the soft phase. Therefore, strong interphase exchange coupling is usually manifested only for nanostructured materials, [11] and the fabrication method and resulting micro-and nanostructure have strong impact on the final magnetic properties of hard/soft nanocomposites and multilayers. [12,13] In crystalline heterostructures, the exchange coupling is often reduced at the interfaces due to structural transitions, defects, or both. [14-16] Multilayers and composites made using amorphous alloys have the advantage that undesirable effects from, for example, atomic steps at interfaces and other structural defects are avoided simply by the amorphous nature, resulting in smooth and continuous interfaces. [17,18] The alternative, to produce high quality epitaxial heterostructures of hard/soft magnets, is a much more cumbersome route toward smooth interfaces. [19] In addition, the epitaxial growth is limited to specific phases with matching lattice constants and specific magnetic properties. The magnetic properties of many amorphous building blocks can, on the other hand, be tuned almost continuously through their composition. [17,20] The sputter process allows industrial-scale production of amorphous multilayers with smooth interfaces, while recent advances in additive manufacturing of amorphous Febased materials open up new perspectives to create amorphous composite magnets of larger sizes and different shapes. [21,22] Electrification of vehicles and renewable energy is increasing the demand for permanent magnets, but the cost and scarcity of rare-earth metals is an obstacle. Creating nanocomposites of rigidly exchange-coupled hard and soft magnets, for which the magnetization reversal occurs as in a single magneticphase material, is a promising route toward rare-earth-lean permanent magnets with high energy products. The hard/soft exch...

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Section: Introductionmentioning

confidence: 99%

Rigid Exchange Coupling in Rare‐Earth‐Lean Amorphous Hard/Soft Nanocomposites

Rani

Muscas

Stopfel

et al. 2020

Adv Elect Materials

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“…Linearly polarized harmonics can be used to probe magnetization by using resonant magneto-optical (MO) effects, such as the magneto-optical Kerr effect (MOKE) [14,15], with transverse (T-MOKE) being the preferred geometry with HHG, or resonant magnetic scattering [16,17]. These MO effects have been successfully exploited at HHG or other XUV sources during the past 10 years to study new aspects of ultrafast magnetization dynamics, such as element-specific or nanometer-scale dynamics [18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Resonant Faraday effect using high-order harmonics for the investigation of ultrafast demagnetization

et al. 2019

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During the past few years high-order harmonic generation (HHG) has opened up the field of ultrafast spectroscopy to an ever larger community by providing a table-top and affordable femtosecond extreme ultraviolet (EUV) and soft-x-ray source. In particular, the field of femtomagnetism has largely benefited from the development of these sources. However, the use of x-ray magnetic circular dichroism (XMCD) as a probe of magnetization, the most versatile and reliable one, has been constrained by the lack of polarization control at HHG sources, so studies have relied on more specific magneto-optical effects. Even the recent developments on the generation of elliptically polarized harmonics have only resulted in a few time-resolved experiments relying on this powerful technique since they add complexity to already-difficult measurements. In this article we show how to easily probe magnetization dynamics with linearly polarized EUV or soft-x-ray light with a versatility similar to XMCD by exploiting the Faraday effect. Static and time-resolved measurements of the Faraday effect are presented around the Co M edges. Using simple theoretical considerations, we show how to retrieve the samples magnetization dynamics from the Faraday rotation and ellipticity transients. Ultrafast demagnetization dynamics of a few nanometers in Co-based samples are measured with this method in out-of-plane as well as in-plane magnetization configurations, showing its great potential for the study of femtomagnetism.

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“…Following the development of femtosecond light sources such as synchrotron radiation (SR) sources using a laser slicing technique, the free electron laser (FEL) and the high harmonic generation (HHG) laser, the RMOKE technique used in combination with these state-of-the-art light sources is becoming increasingly important, particularly for temporal domain measurements in the subpicosecond timescale. We first demonstrated time-resolved RMOKE (TR-RMOKE) measurements using the FEL in 2015 [15]. In this review, we clarify the importance of the RMOKE technique when using an extreme ultraviolet (EUV) FEL from the methodological view point and demonstrate time-resolved RMOKE measurements using a seeded FEL at FERMI@Elettra (FERMI-I is generally called X-ray ultraviolet (XUV) FEL).…”

Section: Introductionmentioning

confidence: 99%

Measurement of the Resonant Magneto-Optical Kerr Effect Using a Free Electron Laser

Yamamoto

Matsuda

2017

Applied Sciences

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We present a new experimental magneto-optical system that uses soft X-rays and describe its extension to time-resolved measurements using a free electron laser (FEL). In measurements of the magneto-optical Kerr effect (MOKE), we tune the photon energy to the material absorption edge and thus induce the resonance effect required for the resonant MOKE (RMOKE). The method has the characteristics of element specificity, large Kerr rotation angle values when compared with the conventional MOKE using visible light, feasibility for M-edge, as well as Ledge measurements for 3d transition metals, the use of the linearly-polarized light and the capability for tracing magnetization dynamics in the subpicosecond timescale by the use of the FEL. The time-resolved (TR)-RMOKE with polarization analysis using FEL is compared with various experimental techniques for tracing magnetization dynamics. The method described here is promising for use in femtomagnetism research and for the development of ultrafast spintronics.

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Ultrafast spin-switching of a ferrimagnetic alloy at room temperature traced by resonant magneto-optical Kerr effect using a seeded free electron laser

Cited by 22 publications

References 28 publications

Rigid Exchange Coupling in Rare‐Earth‐Lean Amorphous Hard/Soft Nanocomposites

Rigid Exchange Coupling in Rare‐Earth‐Lean Amorphous Hard/Soft Nanocomposites

Resonant Faraday effect using high-order harmonics for the investigation of ultrafast demagnetization

Measurement of the Resonant Magneto-Optical Kerr Effect Using a Free Electron Laser

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