Emergent Magnetic Order and Spin Dynamics in a Ytterbium-Based Triangular-Lattice Delafossite

We have synthesized a new member of the AYbX₂ (A = monovalent cation; X = O, S, Se, Te) delafossite family and investigated its magnetic properties using magnetization and heat-capacity measurements. At zero magnetic field, the system shows no evidence of long-range magnetic order down to 20 mK. When a magnetic field is applied along the ab-plane, multiple field-induced magnetic phases emerge above ~2.5 T, followed by full spin polarization near 17 T. The material exhibits stronger exchange interactions compared to other known Yb-based delafossites. We will discuss the magnetic phase transitions and the evolution of the spin dynamics under applied fields. The heat-capacity results suggest the presence of a possible quantum spin liquid phase at low temperatures and low magnetic fields, highlighting this system as a promising platform for exploring quantum spin liquid physics.