Physics

Similar Ultrafast Dynamics Of Several Dissimilar Dirac And Weyl Semimetals, Christopher P. Weber, Bryan S. Berggren, Madison G. Masten, Thomas C. Ogloza, Skylar Deckoff-Jones, Julien Madéo, Michael K. L. Man, Keshav M. Dani, Lingxiao Zhao, Genfu Chen, Jinyu Liu, Zhiqiang Mao, Leslie M. Schoop, Bettina V. Lotsch, Stuart S. P. Parkin, Mazhar Ali

Recent years have seen the rapid discovery of solids whose low-energy electrons have a massless, linear dispersion, such as Weyl, line-node, and Dirac semimetals. The remarkable optical properties predicted in these materials show their versatile potential for optoelectronic uses. However, little is known of their response in the picoseconds after absorbing a photon. Here, we measure the ultrafast dynamics of four materials that share non-trivial band structure topology but that differ chemically, structurally, and in their low-energy band structures: ZrSiS, which hosts a Dirac line node and Dirac points; TaAs and NbP, which are Weyl semimetals; and Sr_{1–y …}

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Ambipolar Spin Diffusion In P-Type Gaas: A Case Where Spin Diffuses More Than Charge, F. Cadiz, V. Notot, J. Filipovic, Christopher P. Weber, L. Martinelli, A.C. H. Rowe, S. Arscott

Physics

We investigate the diffusion of charge and spin at 15 K in p-type GaAs, combining transient-grating and energy-resolved microluminescence measurements to cover a broad range of photoelectron density. At very low optical power, in a unipolar nondegenerate regime, charge and spin diffuse at the same rate, implying that the spin-drag effects are negligible. Upon increasing the photoelectron concentration up to about 1016 cm–3, the charge diffusion constant decreases because of ambipolar electrostatic interactions with the slower-diffusing holes while the spin diffusion constant is reduced only weakly by the ambipolar interaction. A further increase in the excitation power causes increases in …

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Room-Temperature Self-Powered Energy Photodetector Based On Optically Induced Seebeck Effect In Cd3As2, Niloufar Yavarishad, Tahereh Hosseini, Elaheh Kheirandish, Christopher P. Weber, Nikolai Kouklin

Physics

We demonstrate an intrinsically fast Seebeck-type metal–semimetal–metal infrared photodetector based on Cd₃As₂ crystals. The Seebeck voltage is induced under off-center illumination, leading to asymmetric temperature gradients and a net current flow. The room-temperature responsivity of the sensor is 0.27 mA/W. The photocurrent signal is readily registered at a modulation frequency of 6 kHz, and the intrinsic bandwidth of the sensor is predicted to approach the terahertz range. The photocurrent depends on the optical power and modulation frequency. Our study demonstrates that crystallineCd₃As₂ is a promising material for high-bandwidth and spectrally broad photosensing, imaging, and …

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Full-Text Articles in Physics

Physics

Ambipolar Spin Diffusion In P-Type Gaas: A Case Where Spin Diffuses More Than Charge, F. Cadiz, V. Notot, J. Filipovic, Christopher P. Weber, L. Martinelli, A.C. H. Rowe, S. Arscott

Physics

Room-Temperature Self-Powered Energy Photodetector Based On Optically Induced Seebeck Effect In Cd3As2, Niloufar Yavarishad, Tahereh Hosseini, Elaheh Kheirandish, Christopher P. Weber, Nikolai Kouklin

Physics