Intrinsic ultrafast edge photocurrent dynamics in WTe$_2$ driven by broken crystal symmetry
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866909979549630464 |
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| author | Chatterjee, Subhashri Yoshioka, Katsumasa Wakamura, Taro Perebeinos, Vasili Kumada, Norio |
| author_facet | Chatterjee, Subhashri Yoshioka, Katsumasa Wakamura, Taro Perebeinos, Vasili Kumada, Norio |
| contents | Directional photocurrents in two-dimensional materials arise from broken crystal symmetry, offering pathways to high-speed, bias-free photodetection beyond conventional devices. Tungsten ditelluride (WTe$_2$), a type-II Weyl semimetal, exhibits robust symmetry-breaking-induced edge photocurrents from competing nonlinear optical and photothermoelectric mechanisms, whose intrinsic dynamics have remained experimentally inaccessible. Here, we directly resolve sub-picosecond edge photocurrent dynamics in WTe$_2$ through ohmic contacts over temperatures from 300 K to 4 K. We demonstrate ultrafast optical-to-electrical conversion with a 3 dB bandwidth of $\sim$250 GHz and reveal picosecond-timescale switching of the net photocurrent direction below 150 K, linked to a Lifshitz transition. This transient bipolar response arises from non-equilibrium Seebeck effects due to asymmetric cooling of hot electrons and holes. These findings reveal previously hidden ultrafast dynamics in symmetry-engineered materials, offering new strategies to disentangle competing photocurrent mechanisms and enabling the development of self-powered, ultrafast optoelectronic devices. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2510_06618 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Intrinsic ultrafast edge photocurrent dynamics in WTe$_2$ driven by broken crystal symmetry Chatterjee, Subhashri Yoshioka, Katsumasa Wakamura, Taro Perebeinos, Vasili Kumada, Norio Mesoscale and Nanoscale Physics Materials Science Applied Physics Optics Directional photocurrents in two-dimensional materials arise from broken crystal symmetry, offering pathways to high-speed, bias-free photodetection beyond conventional devices. Tungsten ditelluride (WTe$_2$), a type-II Weyl semimetal, exhibits robust symmetry-breaking-induced edge photocurrents from competing nonlinear optical and photothermoelectric mechanisms, whose intrinsic dynamics have remained experimentally inaccessible. Here, we directly resolve sub-picosecond edge photocurrent dynamics in WTe$_2$ through ohmic contacts over temperatures from 300 K to 4 K. We demonstrate ultrafast optical-to-electrical conversion with a 3 dB bandwidth of $\sim$250 GHz and reveal picosecond-timescale switching of the net photocurrent direction below 150 K, linked to a Lifshitz transition. This transient bipolar response arises from non-equilibrium Seebeck effects due to asymmetric cooling of hot electrons and holes. These findings reveal previously hidden ultrafast dynamics in symmetry-engineered materials, offering new strategies to disentangle competing photocurrent mechanisms and enabling the development of self-powered, ultrafast optoelectronic devices. |
| title | Intrinsic ultrafast edge photocurrent dynamics in WTe$_2$ driven by broken crystal symmetry |
| topic | Mesoscale and Nanoscale Physics Materials Science Applied Physics Optics |
| url | https://arxiv.org/abs/2510.06618 |