Chen Zhongqiang, Qiu Hongsong, Cheng Xinjuan, Cui Jizhe, Jin Zuanming, Tian Da, Zhang Xu, Xu Kankan, Liu Ruxin, Niu Wei, Zhou Liqi, Qiu Tianyu, Chen Yequan, Zhang Caihong, Xi Xiaoxiang, Song Fengqi, Yu Rong, Zhai Xuechao, Jin Biaobing, Zhang Rong, Wang Xuefeng
Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, State Key Laboratory of Spintronics Devices and Technologies, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China.
Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, MOE Key Laboratory of Optoelectronic Devices and Systems with Extreme Performances, Nanjing University, 210093, Nanjing, China.
Nat Commun. 2024 Mar 23;15(1):2605. doi: 10.1038/s41467-024-46821-8.
Nonlinear transport enabled by symmetry breaking in quantum materials has aroused considerable interest in condensed matter physics and interdisciplinary electronics. However, achieving a nonlinear optical response in centrosymmetric Dirac semimetals via defect engineering has remained a challenge. Here, we observe the helicity dependent terahertz emission in Dirac semimetal PtTe thin films via the circular photogalvanic effect under normal incidence. This is activated by a controllable out-of-plane Te-vacancy defect gradient, which we unambiguously evidence with electron ptychography. The defect gradient lowers the symmetry, which not only induces the band spin splitting but also generates the giant Berry curvature dipole responsible for the circular photogalvanic effect. We demonstrate that the THz emission can be manipulated by the Te-vacancy defect concentration. Furthermore, the temperature evolution of the THz emission features a minimum in the THz amplitude due to carrier compensation. Our work provides a universal strategy for symmetry breaking in centrosymmetric Dirac materials for efficient nonlinear transport.
量子材料中对称性破缺所实现的非线性输运，在凝聚态物理和跨学科电子学领域引起了广泛关注。然而，通过缺陷工程在中心对称狄拉克半金属中实现非线性光学响应仍是一项挑战。在此，我们通过正常入射下的圆光电流效应，观测到狄拉克半金属PtTe薄膜中与螺旋度相关的太赫兹发射。这一效应由可控的面外碲空位缺陷梯度激活，我们通过电子叠层成像明确证实了这一点。缺陷梯度降低了对称性，这不仅诱导了能带自旋分裂，还产生了负责圆光电流效应的巨大贝里曲率偶极子。我们证明太赫兹发射可通过碲空位缺陷浓度进行调控。此外，由于载流子补偿，太赫兹发射的温度演化呈现出太赫兹振幅的最小值。我们的工作为中心对称狄拉克材料中的对称性破缺以实现高效非线性输运提供了一种通用策略。
