Manipulating vacancy in Yb triangular lattice materials for the quantum disordered states

Yb triangular-lattice materials have attracted attention due to their potential to host exotic magnetic quantum states. In this talk, we will present our recent study on Yb-based triangular-lattice compounds with vacancy disorder, focusing on their structural and magnetic properties. Single-crystal X-ray diffraction reveals notable Cu-site vacancies in both CuYbSe₂ and Cu_2.73YbP₂. Magnetic susceptibility measurements indicate dominant antiferromagnetic interactions and an effective spin-1/2 state of Yb³⁺. No magnetic ordering is observed down to 0.4 K in CuYbSe₂, supporting a quantum-disordered ground state and suggesting its candidacy as aquantum spin liquid. In contrast, Cu_2.73YbP₂ exhibits clear evidence of spin freezing at 4.5 K in both magnetization and heat capacity, consistent with a spin-glass state. In addition to the materials themselves, we will also discuss the measurement techniques used to characterize their magnetic behavior.