biostudies-literatureChen ZNational Natural Science Foundation of ChinaNational Natural Science Foundation of China (National Science Foundation of China)2605https://www.ebi.ac.uk/biostudies/studies/S-EPMC10960839biostudies-literatureUnknown15(1)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 PtTe₂ 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 dNature communicationsDefect-induced helicity dependent terahertz emission in Dirac semimetal PtTe₂ thin films.PMC1096083992161201 and 1202540462322115T2394473, T2394470, 62274085, 11874203 and 618224036202780762374088 and 12074193Xi XXu KZhou LQiu HYu RCui JTian DLiu RSong FCheng XJin ZNiu WZhang RChen ZZhai XJin BZhang XQiu TChen YWang XZhang CfalseDefect-induced helicity dependent terahertz emission in Dirac semimetal PtTe₂ thin films.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 PtTe₂ 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 d2024-01-01T00:00:00Z2024 Mar2026-07-15T20:04:56.901Z2025-04-06T13:53:39.386ZS-EPMC109608393852179710.1038/s41467-024-46821-8