PHYSICAL REVIEW MATERIALS 7, 014402 (2023) Magnetic properties and coupled spin-phonon behavior in quasi-one-dimensional screw-chain compound BaMn 2 V 2 O 8 Arkadeb Pal , 1, 2 , * Khyati Anand , 2 , * T. W. Yen, 1 Atanu Patra, 3 A. Das , 4 S. M. Huang, 1 E. Blundo, 3 A. Polimeni, 3 H. D. Yang , 1, 5 , † and Sandip Chatterjee 2 , ‡ 1 Department of Physics, National Sun Yat-sen University, Kaohsiung 804, Taiwan 2 Department of Physics, Indian Institute of Technology (BHU), Varanasi 221005, India 3 Physics Department, Sapienza University of Rome, 00185 Roma, Italy 4 Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India and Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India 5 Center of Crystal Research, National Sun Yat-sen University, Kaohsiung 804, Taiwan (Received 6 August 2022; revised 24 November 2022; accepted 15 December 2022; published 10 January 2023) Spin-chain compounds are known to exhibit fascinating magnetic properties, which mostly display magnetic ordering at very low temperatures or remain dynamic even at 0 K. In contrast, the present quasi-one-dimensional spin-chain system BaMn 2 V 2 O 8 exhibits a collinear antiferromagnetic (AFM) long-range ordering at a relatively higher temperature T N ∼ 37 K, wherein the nearest-neighbor spins have AFM coupling along the spin chain, i.e., along the c axis. The present study also reveals a short-range magnetic ordering prevailing at considerably elevated temperatures above its T N . Temperature-dependent Raman spectroscopy demonstrates an occurrence of spin-phonon coupling below T N at least for two phonon modes, whereas the study also shows an unusual thermal evolution of the Raman modes above T N , which is apparently associated to the short-range magnetic ordering. Furthermore, extensive ab initio density functional theory calculations accompanied with classical Heisenberg model based theoretical calculations of various exchange interaction parameters (J 0 –J 5 ) suggest an AFM ground state, which matches well with the experimentally obtained spin structure. DOI: 10.1103/PhysRevMaterials.7.014402 I. INTRODUCTION The study on low-dimensional magnetic systems has started seeking immense attention globally due to their in- triguing rich magnetic phenomena [1–3]. They also hold promise for their potential applications in quantum compu- tation [3]. The topology and dimensionality of such a spin system as well as its interactions occurring with other micro- scopic order parameters, such as lattice, charge, and orbital degrees of freedom, have a profound influence on its various aspects. In this regard, the research on the one-dimensional (1D) spin-chain systems has been a very active field of ex- perimental as well as theoretical condensed matter physics. In a perfect 1D antiferromagnetic (AFM) spin system, the persistence of strong thermal and quantum fluctuations at low temperatures, which are triggered by macroscopic degener- acy, destroys the long-range ordering (LRO), leading to the well-known exotic phenomenon, spin liquid. Nevertheless, a real quasi-1D AFM spin system can exhibit a spin liquid state, or a three-dimensional (3D) Néel-type, or a XY -type magnetic ordering, which depend on various factors, such as the interchain interactions, magnetic anisotropy, and also spin values [4–6]. In fact, the half-integer spin-chain systems * These authors contributed equally to this work. † yang@mail.nsysu.edu.tw ‡ schatterji.app@iitbhu.ac.in are gapless, wherein a finite interchain interaction leads to the LRO. On the contrary, an integer spin-chain system may exhibit a spin gap by showing a singlet ground state and triplet excited states. In this context, a series of compounds having a chemi- cal formula AM 2 V 2 O 8 (where A = Ba, Sr, Pb; and M = Co, Mn, Ni, Cu) attracted much interest owing to their distinct structures and varied intriguing magnetic properties. Their structure consists of arrays of edge-shared M 2+ O 6 octahe- dra forming screw chains along the crystallographic c axis, leading to a quasi-1D structural arrangement of magnetic ions. Despite having similar crystal structures (although with different crystal symmetries), various AM 2 V 2 O 8 compounds display solely distinct magnetic properties, which vary with a change in the magnetic ions from Cu 2+ to Mn 2+ . The iso- lated spin dimer or alternating spin-chain system BaCu 2 V 2 O 8 shows a large spin gap with a singlet ground state [7]; the honeycomb magnetic system BaNi 2 V 2 O 8 shows a quasi-two- dimensional (2D) AFM ordering (XY type) [8], whereas the Haldane-gap spin-chain AFM systems SrNi 2 V 2 O 8 and PbNi 2 V 2 O 8 exhibit interesting quantum critical phase tran- sition lying in between the spin liquid state and Ising-like magnetic state [9]. On the other hand, the Ising spin sys- tems with strong magnetic anisotropy, viz., BaCo 2 V 2 O 8 , PbCo 2 V 2 O 8 , and SrCo 2 V 2 O 8 compounds display interesting field-driven quantum phase transition [10–12]. Interestingly, unlike the other members of the AM 2 V 2 O 8 family, the S = 5/2 spin-chain compounds, i.e., SrMn 2 V 2 O 8 (T N ∼ 42.2K) 2475-9953/2023/7(1)/014402(12) 014402-1 ©2023 American Physical Society