Evidence of spin-phonon-charge coupling in quasi-one-dimensional Ising spin chain system $\alpha$-CoV$_2$O$_6$

Debismita Naik; Souvick Chakraborty; Akriti Singh; Ayan Mondal; Surajit Saha; Venkataramanan Mahalingam; Satyabrata Raj; Pradip Khatua

arXiv · 2503.19477

Evidence of spin-phonon-charge coupling in quasi-one-dimensional Ising spin chain system $\alpha$-CoV$_2$O$_6$

Debismita Naik·Souvick Chakraborty·Akriti Singh·Ayan Mondal·Surajit Saha·Venkataramanan Mahalingam·Satyabrata Raj·Pradip Khatua

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Abstract

The quasi-one-dimensional Ising spin chain system $\alpha$-CoV$_2$O$_6$ is considered to exhibit fascinating magnetic properties at lower temperatures. We comprehensively study magnetic properties and lattice dynamics using a combination of x-ray diffraction (XRD), DC magnetization, specific heat, temperature-dependent XRD and Raman scattering measurements, along with the theoretical charge density map calculations. The DC magnetization and specific heat confirm the antiferromagnetic (AFM) long-range order (LRO) at Neel temperature T$_N$ = 15 K as well as the short-range ordering (SRO) below 100 K. Temperature-dependent Raman measurement has been performed in the temperature range of 5 K to 180 K, revealing spin-phonon coupling (SPC) below 100 K, which is well above the T$_N$ and is attributed to SRO. The SPC is calculated for different vibrational modes. The temperature-dependent XRD supports the key finding of magnetoelastic coupling at T$_N$, which is strongly correlated to the magnetoelectric phenomena. The renormalization of Raman modes and lattice anomalies near T$_N$ illustrate spin-lattice coupling via magnetoelastic and spin-phonon interactions leading to the interplay between spin, charge, and phonon degrees of freedom in $\alpha$-CoV$_2$O$_6$. The presence of spin-charge coupling is confirmed by the theoretical charge density maps, which show that the formation of electric dipoles between the Co and O atoms in the AFM state results from the p-d hybridization.

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Debismita Naik, Souvick Chakraborty, Akriti Singh, Ayan Mondal, Surajit Saha, Venkataramanan Mahalingam, Satyabrata Raj, Pradip Khatua. 2025-03-25. Evidence of spin-phonon-charge coupling in quasi-one-dimensional Ising spin chain system $\alpha$-CoV$_2$O$_6$. https://arxiv.org/abs/2503.19477

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