Evidence of spin–phonon–charge coupling and spin–orbit excitations in quasi-one-dimensional Ising spin chain system α –CoV 2 O 6

Abstract The quasi-one-dimensional Ising spin chain α –CoV 2 O 6 exhibits intriguing low-temperature magnetic behavior. We report a comprehensive study of the magnetic and lattice properties of the quasi-one-dimensional Ising spin-chain compound α –CoV 2 O 6 using x-ray diffraction, DC magnetization, specific heat, Raman spectroscopy, and theoretical charge density calculations. Antiferromagnetic (AFM) long-range order is observed at T N = 15 K, with short-range magnetic correlations persisting below 100 K. The Co 2+ ions exhibit an effective spin-1/2 ground state due to crystal-field effects and strong spin–orbit coupling. Temperature-dependent Raman and XRD measurements reveal pronounced spin–phonon and magnetoelastic coupling, with anomalies near T N and signatures of short-range ordering well above the magnetic transition. These couplings play a crucial role in stabilizing the magnetic plateau and highlight the interplay between spin, lattice, and charge degrees of freedom. Theoretical charge density calculations confirm spin–charge coupling via p–d hybridization, leading to electric dipole formation in the AFM state.