Observation of momentum-dependent charge density wave gap in a layered antiferromagnet GdTe3

Charge density wave (CDW) ordering has been an important topic of study for a long time owing to its connection with other exotic phases such as superconductivity and magnetism. The RTe3 (R = rare-earth elements) family of materials provides a fertile ground to study the dynamics of CDW in van der Waals layered materials, and the presence of magnetism in these materials allows to explore the interplay among CDW and long range magnetic ordering. Here, we have carried out a high-resolution angle-resolved photoemission spectroscopy (ARPES) study of a CDW material GdTe3, which is antiferromagnetic below 12 K, along with thermodynamic, electrical transport, magnetic, and Raman measurements. Our Raman spectroscopy measurements show the presence of CDW amplitude mode at room temperature, which remains prominent when the sample is thinned down to 4-layers by exfoliation. Our ARPES data show a two-fold symmetric Fermi surface with both gapped and ungapped regions indicative of the partial nesting. The gap is momentum dependent, maximum along G-Z and gradually decreases going towards G - M. Our study provides a platform to study the dynamics of CDW and its interaction with other physical orders in two- and three-dimensions.