Purcell enhancement of photogalvanic currents in a van der Waals plasmonic self-cavity

Fuente: arXiv
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Main Authors: Li, Xinyu, Hagelstein, Jesse, Kipp, Gunda, Sturm, Felix, Kusyak, Kateryna, Huang, Yunfei, Schulte, Benedikt F., Potts, Alexander M., Stensberg, Jonathan, Quirós-Cordero, Victoria, Trovatello, Chiara, Peng, Zhi Hao, Hu, Chaowei, DeStefano, Jonathan M., Fechner, Michael, Taniguchi, Takashi, Watanabe, Kenji, Schuck, P. James, Xu, Xiaodong, Chu, Jiun-Haw, Zhu, Xiaoyang, Rubio, Angel, Michael, Marios H., Day, Matthew W., Bretscher, Hope M., McIver, James W.
Format: Preprint
Published: 2025
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author Li, Xinyu
Hagelstein, Jesse
Kipp, Gunda
Sturm, Felix
Kusyak, Kateryna
Huang, Yunfei
Schulte, Benedikt F.
Potts, Alexander M.
Stensberg, Jonathan
Quirós-Cordero, Victoria
Trovatello, Chiara
Peng, Zhi Hao
Hu, Chaowei
DeStefano, Jonathan M.
Fechner, Michael
Taniguchi, Takashi
Watanabe, Kenji
Schuck, P. James
Xu, Xiaodong
Chu, Jiun-Haw
Zhu, Xiaoyang
Rubio, Angel
Michael, Marios H.
Day, Matthew W.
Bretscher, Hope M.
McIver, James W.
author_facet Li, Xinyu
Hagelstein, Jesse
Kipp, Gunda
Sturm, Felix
Kusyak, Kateryna
Huang, Yunfei
Schulte, Benedikt F.
Potts, Alexander M.
Stensberg, Jonathan
Quirós-Cordero, Victoria
Trovatello, Chiara
Peng, Zhi Hao
Hu, Chaowei
DeStefano, Jonathan M.
Fechner, Michael
Taniguchi, Takashi
Watanabe, Kenji
Schuck, P. James
Xu, Xiaodong
Chu, Jiun-Haw
Zhu, Xiaoyang
Rubio, Angel
Michael, Marios H.
Day, Matthew W.
Bretscher, Hope M.
McIver, James W.
contents Cavities provide a means to manipulate the optical and electronic responses of quantum materials by selectively enhancing light-matter interaction at specific frequencies and momenta. While cavities typically involve external structures, exfoliated flakes of van der Waals (vdW) materials can form intrinsic self-cavities due to their small finite dimensions, confining electromagnetic fields into plasmonic cavity modes, characterized by standing-wave current distributions. While cavity-enhanced phenomena are well-studied at optical frequencies, the impact of self-cavities on nonlinear electronic responses--such as photogalvanic currents--remains largely unexplored, particularly in the terahertz regime, critical for emerging ultrafast optoelectronic technologies. Here, we report a self-cavity-induced Purcell enhancement of photogalvanic currents in the vdW semimetal WTe$_2$. Using ultrafast optoelectronic circuitry, we measured coherent near-field THz emission resulting from nonlinear photocurrents excited at the sample edges. We observed enhanced emission at finite frequencies, tunable via excitation fluence and sample geometry, which we attribute to plasmonic interference effects controlled by the cavity boundaries. We developed an analytical theory that captures the cavity resonance conditions and spectral response across multiple devices. Our findings establish WTe$_2$ as a bias-free, geometry-tunable THz emitter and demonstrate the potential of self-cavity engineering for controlling nonlinear, nonequilibrium dynamics in quantum materials.
format Preprint
id arxiv_https___arxiv_org_abs_2507_07987
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Purcell enhancement of photogalvanic currents in a van der Waals plasmonic self-cavity
Li, Xinyu
Hagelstein, Jesse
Kipp, Gunda
Sturm, Felix
Kusyak, Kateryna
Huang, Yunfei
Schulte, Benedikt F.
Potts, Alexander M.
Stensberg, Jonathan
Quirós-Cordero, Victoria
Trovatello, Chiara
Peng, Zhi Hao
Hu, Chaowei
DeStefano, Jonathan M.
Fechner, Michael
Taniguchi, Takashi
Watanabe, Kenji
Schuck, P. James
Xu, Xiaodong
Chu, Jiun-Haw
Zhu, Xiaoyang
Rubio, Angel
Michael, Marios H.
Day, Matthew W.
Bretscher, Hope M.
McIver, James W.
Mesoscale and Nanoscale Physics
Optics
Cavities provide a means to manipulate the optical and electronic responses of quantum materials by selectively enhancing light-matter interaction at specific frequencies and momenta. While cavities typically involve external structures, exfoliated flakes of van der Waals (vdW) materials can form intrinsic self-cavities due to their small finite dimensions, confining electromagnetic fields into plasmonic cavity modes, characterized by standing-wave current distributions. While cavity-enhanced phenomena are well-studied at optical frequencies, the impact of self-cavities on nonlinear electronic responses--such as photogalvanic currents--remains largely unexplored, particularly in the terahertz regime, critical for emerging ultrafast optoelectronic technologies. Here, we report a self-cavity-induced Purcell enhancement of photogalvanic currents in the vdW semimetal WTe$_2$. Using ultrafast optoelectronic circuitry, we measured coherent near-field THz emission resulting from nonlinear photocurrents excited at the sample edges. We observed enhanced emission at finite frequencies, tunable via excitation fluence and sample geometry, which we attribute to plasmonic interference effects controlled by the cavity boundaries. We developed an analytical theory that captures the cavity resonance conditions and spectral response across multiple devices. Our findings establish WTe$_2$ as a bias-free, geometry-tunable THz emitter and demonstrate the potential of self-cavity engineering for controlling nonlinear, nonequilibrium dynamics in quantum materials.
title Purcell enhancement of photogalvanic currents in a van der Waals plasmonic self-cavity
topic Mesoscale and Nanoscale Physics
Optics
url https://arxiv.org/abs/2507.07987