Differentiating contributions of electrons and phonons to the thermoreflectance spectra of gold

Liu, Kexin; Shi, Xinping; Angeles, Frank; Mohan, Ramya; Gorchon, Jon; Coh, Sinisa; Wilson, R. B.

doi:10.1103/physrevmaterials.5.106001

Cited by 7 publications

(2 citation statements)

References 71 publications

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“…The Fermi-Dirac distribution occupation factor is denoted as 𝑓 while velocity operator is 𝑣. 𝜂 𝑚𝑛𝒌 describes the effect of electronic scattering rates on transitions due to electron scattering. We model 𝜂 𝑚𝑛𝒌 with spin-independent electron-electron and electronphonon scattering which reproduces both first-principles calculations [34]. We also add to 𝜂 𝑚𝑛𝒌 constant spin-independent extrinsic scattering of 0.1 eV to correctly reproduce the imaginary part of the diagonal component of the conductivity tensor [35].…”

Section: A Theorymentioning

confidence: 99%

Magneto-optical Kerr spectra of gold induced by spin accumulation

2022

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We report the magneto optic Kerr effect (MOKE) angle of Au magnetically excited by spin accumulation. We perform time resolved polar MOKE measurements on Au/Co heterostructures. In our experiment, the ultrafast optical excitation of the Co drives spin accumulation into an adjacent Au layer. The spin accumulation, together with spin-orbit coupling, leads to non-zero terms in the off-diagonal conductivity tensor of Au, which we measure by recording the polarization and ellipticity of light reflected from the Au surface for photon energies between 1.3 and 3.1 eV. In a narrow energy range near the interband transition threshold of Au, the sensitivity to magnetization measured exceeds 1 µrad per A/m. In the photon energy interval of 0.6 -4.4 eV, the maximum value for transition ferromagnetic metals like Ni are < 10 nrad per A/m, while predicted values for heavy metals like Pt or W are < 13 nrad per A/m. The exceptional sensitivity of the optical properties of Au to spin magnetic moments make Au to be an exceptionally sensitive optical magnetometer, with potential applications in the development of optospintronic technologies.

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Section: A Theorymentioning

confidence: 99%

Magneto-optical Kerr spectra of gold induced by spin accumulation

2022

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“…It is known that phonon–phonon coupling could also promote thermal diffusion inside the lattice system. [ 45 ] After 4 ns, the lattice temperatures at selected points became completely equal. The whole system cooled down to room temperature before subsequent laser pulse arrival.…”

Section: Resultsmentioning

confidence: 99%

Metal Nanoparticles Assisted Ultrafast Laser Plasmonic Microwelding of Oxide–Semiconductor Interconnects

Hu,

Lin,

et al. 2024

Small Methods

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Integration of wafer‐scale oxide and semiconductor materials meets the difficulties of residual stress and materials incompatibility. In this work, Ag NPs thin film is contributed as an energy confinement layer between oxide (Sapphire) and semiconductor (Si) wafers to localize the materials interaction during ultrafast laser irradiation. Due to the plasmonic effects generated within constructed dielectric–metal–dielectric structures (i.e., Sapphire–Ag–Si), thermal diffusion and chemical reaction between Ag and its neighboring materials facilitate the microwelding of Sapphire and Si wafers. Ag NPs can be totally sintered within the junction area to bridge oxide and semiconductor, while Al─O─Ag bond and Ag─Si bond are formed at Ag–Sapphire and Ag─Si interfaces, respectively. As‐received heterogeneous joint exhibits a high shear strength up to 5.4 MPa, with the fracture occurring inside Si wafer. Meanwhile, insertion of metal nanolayer can greatly relieve the residual stress‐induced microcracking inside the brittle materials. Such wafer‐scale Sapphire and Si interconnects thus show robust strength and excellent impermeability even after thermal shocking (−40 °C to 120 °C) for 200 cycles. This metal NPs layer‐assisted plasmonic microwelding technology can extend to broad materials integration, which is promising for high‐performance microdevices development in MEMS, MOEMS, or microfluidics.

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Thermal model for time-domain thermoreflectance experiments in a laser-flash geometry

Peng

Wilson

2022

Journal of Applied Physics

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Time-domain thermoreflectance (TDTR) is a well-established pump–probe method for measuring thermal conductivity and interface conductance of multilayers. Interpreting signals in a TDTR experiment requires a thermal model. In standard front/front TDTR experiments, both pump and probe beams typically irradiate the surface of a multilayer. As a result, existing thermal models for interpreting thermoreflectance experiments assume that the pump and probe beams both interact with the surface layer. Here, we present a frequency-domain solution to the heat-diffusion equation of a multilayer in response to nonhomogeneous laser heating. This model allows analysis of experiments where the pump and probe beams irradiate opposite sides of a multilayer. We call such a geometry a front/back experiment to differentiate such experiments from standard TDTR experiments. As an example, we consider a 60nm amorphous Si film. We consider how signals differ in a front/front vs front/back geometry and compare thermal model predictions to experimental data.

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Differentiating contributions of electrons and phonons to the thermoreflectance spectra of gold

Cited by 7 publications

References 71 publications

Magneto-optical Kerr spectra of gold induced by spin accumulation

Magneto-optical Kerr spectra of gold induced by spin accumulation

Metal Nanoparticles Assisted Ultrafast Laser Plasmonic Microwelding of Oxide–Semiconductor Interconnects

Thermal model for time-domain thermoreflectance experiments in a laser-flash geometry

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