Applied-field magnetic structure and spectroscopy shifts of the effective spin-$\frac{1}{2}$, $XY$-like magnet Li$_2$CoCl$_4$

Zachary W. Riedel; Mykhaylo Ozerov; Stuart Calder; Daniel P. Shoemaker

doi:10.1103/tqwb-v5r2

paper

Applied-field magnetic structure and spectroscopy shifts of the effective spin- $\frac{1}{2}$ , $X Y$ -like magnet Li $_{2}$ CoCl $_{4}$

arXiv:2503.05101 · doi:10.1103/tqwb-v5r2

Abstract

Insulators containing chains of magnetic transition metal cations provide platforms for probing spin- $\frac{1}{2}$ dynamics and quantum critical behavior. Li $_{2}$ CoCl $_{4}$ contains edge-sharing CoCl $_{6}$ octahedra that form chains along the crystallographic $c$ axis and orders antiferromagnetically at zero field, but questions remain about its applied-field magnetic structure and the Co $^{2 +}$ spin state. Here, we show with neutron diffraction on a polycrystalline sample how the anti-aligned chains of cobalt moments begin to transition to a ferromagnetic state above 1.6 T. Further, using magnetic resonance absorption measurements and noninteracting spin models, we reveal the strongly anisotropic nature of the Co $^{2 +}$ ion's $X Y$ -like magnetic behavior ( $g_{∥} = 2.77$ and $g_{⊥} = 5.23$ ) and its $J = \frac{1}{2}$ ground state. We, therefore, supply the magnetic structures and anisotropic description needed to explore the dynamics of the field-driven magnetic phases, laying the foundation for further experimental and theoretical studies.

arXiv comment24 pages, 19 figures; v2 updates the high-field neutron diffraction interpretation, adds details to the IR data analysis, and re-organizes the manuscript sections; v3 provides minor updates to the abstract and the neutron diffraction section

Applied-field magnetic structure and spectroscopy shifts of the effective spin-21​, XY-like magnet Li2​CoCl4​

Abstract

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Applied-field magnetic structure and spectroscopy shifts of the effective spin- $\frac{1}{2}$ , $X Y$ -like magnet Li $_{2}$ CoCl $_{4}$