Colossal angular magnetoresistance in the antiferromagnetic semiconductor EuTe2

With a surge of interest in antiferromagnetic (AFM) spintronics, the manipulation and detection of different AFM states has become a topic of concern. In particular, a large magnetoresistive response is of critical importance for facilitating the readout of AFM states. Here, we report the observation of colossal angular magnetoresistance (AMR) in a layered AFM rare-earth dichalcogenide, EuTe2. The AMR reaches -40 000% at 2 K and 22 kOe, which is approximately four orders of magnitude larger than in AFM metals and alloys. Combined magnetization, resistivity, and theoretical analysis reveal strong coupling of the electronic state (metal vs insulator) to the vector spins, which mainly arises from the space-time inversion symmetry-broken correlated band reconstruction. Consequently, the anisotropic magnetization response to the vector magnetic field induces metal-insulator transition (MIT) and a large anisotropic magnetotransport that explains the experimental findings very well. These results suggest an avenue for exploring the spin configuration dependent transport properties for unique AFM spintronic devices.