Magnetic field induced Weyl state in the van der Waals–type antiferromagnet GdTe3

${\mathrm{GdTe}}_{3}$, a van der Waals--type antiferromagnetic (AFM) metal with high mobility, is gaining a lot of attention for its potential use in high-speed spintronic devices as well as for fundamental physics research. Due to the magnetocrystalline anisotropy of ${\mathrm{GdTe}}_{3}$, exotic effects are envisaged, when the magnetic configurations interact with an external magnetic field. In this work, a magnetic-field-induced Weyl state in ${\mathrm{GdTe}}_{3}$ is revealed. In the AFM state, ${\mathrm{GdTe}}_{3}$ is topologically trivial. However, when an external magnetic field exceeding $\ensuremath{\sim}20$ T aligns all spins, band splitting occurs, and then a topological transition is induced, i.e., from a trivial metallic state to a topological Weyl metallic state. In addition, a topological change of Fermi surfaces, i.e., a field-induced Lifshitz transition, is uncovered, which may also be rooted in band splitting. Moreover, high-pressure electrical transport measurements reveal a peculiar superconducting transition with a nearly invariant superconducting transition temperature (${T}_{c}\ensuremath{\sim}4.2$ K) spanning a wide range of pressure up to 48 GPa. These findings imply that ${\mathrm{GdTe}}_{3}$ provides a unique platform for investigating not only the interactions of charge-density-wave fluctuations and superconductivity but also the interplay between magnetism and topology.