# Intrinsic Negative Magnetoresistance and Broadband Photoresponse in Magnetic van der Waals Crystal TaFeTe2

## TL;DR

TaFeTe2 is a 2D magnetic material with unique properties like negative magnetoresistance and broadband light detection, making it promising for advanced electronics.

## Contribution

The discovery of intrinsic negative magnetoresistance and self-powered broadband photoresponse in TaFeTe2 crystals.

## Key findings

- TaFeTe2 shows intrinsic unsaturated negative magnetoresistance up to 9 T.
- Photodetectors made from TaFeTe2 achieve a high responsivity of 0.18 A W−1.
- The material exhibits broadband photoresponse from visible to mid-infrared light.

## Abstract

2D van der Waals (vdW) materials with broken symmetry, such as MM′Te2 (where M═Nb, Ta, and M′ = Fe, Co, Ni), have attracted considerable research interest due to their unique magnetic structures and optical‐phonon‐induced phase transitions, providing a versatile platform for discovering novel physical phenomena. Here, we report the synthesis of TaFeTe2 single crystals that can be mechanically exfoliated to the 2D limit. The as‐grown crystals display characteristic spin‐glass behavior and intrinsic unsaturated negative magnetoresistance up to 9 T, likely arising from the orbital effect associated with variable‐range hopping transport and/or magnetic disordering. Notably, TaFeTe2‐based photodetectors exhibit robust photocurrent responses in the sample's interior under self‐powered conditions, primarily arising from an additional charge separation mechanism induced by the optical‐phonon‐triggered non‐centrosymmetric phase. Under standard bias, the detectors achieve a high responsivity of 0.18 A W−1 and broadband photoresponse spanning the visible to mid‐infrared spectrum. These features highlight the material's strong potential for advanced multifunctional optoelectronic applications.

2D van der Waals (vdW) materials MM′Te2 with broken symmetry attract great interest for unique magnetic structures and optical‐phonon‐induced phase transitions. We report mechanically exfoliable TaFeTe2 single crystals, exhibiting spin‐glass behavior, intrinsic unsaturated negative magnetoresistance up to 9 T, self‐powered internal photocurrent, and visible‐mid‐infrared broadband photoresponse, showing great potential for advanced multifunctional optoelectronics.