Negative Photoconductivity of Fe 3 GeTe 2 Crystal with Native Heterostructure for Ultraviolet to Terahertz Ultra-Broadband Photodetection.

Gaining insight into the photoelectric behavior of ferromagnetic materials is significant for comprehensively grasping their intrinsic properties and broadening future application fields. Here, through a specially designed Fe 3 GeTe 2 /O-Fe 3 GeTe 2 heterostructure, we first report the broad-spectrum negative photoconductivity phenomenon of ferromagnetic nodal line semimetal Fe 3 GeTe 2 that covers ultraviolet-visible-infrared-terahertz bands (355 nm - 3000 μm), promising to compensate for the inadequacies of traditional optoelectronic devices. The significant suppression of photoexcitation conductivity is revealed to arise from the semimetal/oxidation (sMO) interface-assisted dual-response mechanism, in which the electron excitation origins from the semiconductor photoconductivity effect in high-energy photon region, and semimetal topological band-transition in low-energy photon region. High responsivities ranging from 10 3 to 10 0  mA W -1 are acquired within ultraviolet-terahertz bands under ±0.1 V bias voltage at room temperature. Notably, the responsivity of 2.572 A W -1 at 3000 μm (0.1 THz) and the low noise equivalent power of 26 pW Hz -1/2 surpass most state-of-the-art mainstream terahertz detectors. This research provides a new perspective for revealing the photoelectric conversion properties of Fe 3 GeTe 2 crystal and paves the way for the development of spin-optoelectronic devices. This article is protected by copyright. All rights reserved.