Ultrafast demagnetization of FePt:Cu thin films and the role of magnetic heat capacity

Kimling, Johannes; Kimling, Judith; Wilson, R. B.; Hebler, Birgit; Albrecht, Manfred; Cahill, David G.

doi:10.1103/physrevb.90.224408

Cited by 60 publications

(53 citation statements)

References 40 publications

(81 reference statements)

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“…Integration of Eq. (27) and multiplication of the result with the density of states at the Fermi energy gives the number of spins per unit area due to the SDSE,…”

Section: A Approximation I: Zero Charge Currentmentioning

confidence: 99%

Spin diffusion induced by pulsed-laser heating and the role of spin heat accumulation

Kimling

Cahill

2017

Phys. Rev. B

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We present a model for describing spin-diffusion in normal metal/ferromagnetic metal heterostructures induced by pulsed-laser heating. The model is based on the assumptions that electronic heat currents give rise to the spin-dependent Seebeck effect and that ultrafast demagnetization generates spin accumulation with a rate proportional to the demagnetization rate measured. Spin-diffusion currents are then driven by gradients in spin accumulation and electron temperature.The model considers spin-dependent thermal conductivity and electron-phonon coupling, which can give rise to different effective temperatures for majority and minority spins, known as spin heat accumulation. We find that spin heat accumulation can significantly enhance the spin-dependent Seebeck effect.

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“…Integration of Eq. (27) and multiplication of the result with the density of states at the Fermi energy gives the number of spins per unit area due to the SDSE,…”

Section: A Approximation I: Zero Charge Currentmentioning

confidence: 99%

Spin diffusion induced by pulsed-laser heating and the role of spin heat accumulation

Kimling

Cahill

2017

Phys. Rev. B

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“…The thermalization time of electrons and phonons in the Co layers is much shorter than the duration of the laser pulse, i.e., only a small amount of the energy of the laser pulse is stored in the electron reservoir after the pulse 28 . This means that the sensitivity of the three-temperature model to the electronic heat capacity C e = C ↑ + C ↓ is negligibly small.…”

Section: Spin-dependent Thermal Diffusion Model For a Periodic Multilmentioning

confidence: 99%

Spin-dependent thermal transport perpendicular to the planes of Co/Cu multilayers

et al. 2015

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We report measurements of the cross-plane thermal conductivity of periodic Co/Cu multilayers using time-domain thermoreflectance. The cross-plane thermal conductivity increases from ∼ 18 W m −1 K −1 at remanence to ∼ 32 W m −1 K −1 at saturation fields. This giant magnetothermal resistance (GMTR) effect is consistent with predictions based on the Wiedemann-Franz law.We discuss the role of a spin-dependent temperature, known as spin heat accumulation, in GMTR experiments and develop a three-temperature model capable of predicting the time-evolution of the temperatures of majority-spin electrons, minority-spin electrons, and phonons subsequent to pulsed laser heating.

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“…A third suggestion had been made by Kimling et al,131 using the spin specific heat as it diverges at around T C itself in the modeling. While, in principle, spin-fluctuations are captured in the LLB and M3TM models via the slope of M(T) that enters as a slowing down of the spin system's response via the dynamics susceptibility, there is no feedback loop for the spin system to the electrons or phonons.…”

Section: Theoretical Perspectivesmentioning

confidence: 99%

Perspective: Ultrafast magnetism and THz spintronics

Walowski

Münzenberg

2016

Journal of Applied Physics

325

205

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This year the discovery of femtosecond demagnetization by laser pulses is 20 years old. For the first time, this milestone work by Bigot and coworkers gave insight directly into the time scales of microscopic interactions that connect the spin and electron system. While intense discussions in the field were fueled by the complexity of the processes in the past, it now became evident that it is a puzzle of many different parts. Rather than providing an overview that has been presented in previous reviews on ultrafast processes in ferromagnets, this perspective will show that with our current depth of knowledge the first applications are developed: THz spintronics and all-optical spin manipulation are becoming more and more feasible. The aim of this perspective is to point out where we can connect the different puzzle pieces of understanding gathered over 20 years to develop novel applications. Based on many observations in a large number of experiments. Differences in the theoretical models arise from the localized and delocalized nature of ferromagnetism. Transport effects are intrinsically non-local in spintronic devices and at interfaces. We review the need for multiscale modeling to address the processes starting from electronic excitation of the spin system on the picometer length scale and sub-femtosecond time scale, to spin wave generation, and towards the modeling of ultrafast phase transitions that altogether determine the response time of the ferromagnetic system. Today, our current understanding gives rise to the first usage of ultrafast spin physics for ultrafast magnetism control: THz spintronic devices. This makes the field of ultrafast spin-dynamics an emerging topic open for many researchers right now. Published by AIP Publishing. [http://dx

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Ultrafast demagnetization of FePt:Cu thin films and the role of magnetic heat capacity

Cited by 60 publications

References 40 publications

Spin diffusion induced by pulsed-laser heating and the role of spin heat accumulation

Spin diffusion induced by pulsed-laser heating and the role of spin heat accumulation

Spin-dependent thermal transport perpendicular to the planes of Co/Cu multilayers

Perspective: Ultrafast magnetism and THz spintronics

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