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arXiv · 2301.06501

Polaronic and Mott insulating phase of layered magnetic vanadium trihalide VCl3

Dario Mastrippolito·Luigi Camerano·Hanna Swiatek·Břetislav Šmíd·Tomasz Klimczuk·Luca Ottaviano·Gianni Profeta
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Abstract

Two-dimensional (2D) van der Waals (vdW) magnetic $3d$-transition metal trihalides are a new class of functional materials showing exotic physical properties useful for spintronic and memory storage applications. In this article, we report the synthesis and electromagnetic characterization of single-crystalline vanadium trichloride, VCl$_3$, a novel 2D layered vdW Mott insulator, which has a rhombohedral structure (R$\overline{3}$, No. 148) at room temperature. VCl$_3$ undergoes a structural phase transition at 103 K and a subsequent antiferromagnetic transition at 21.8 K. Combining core levels and valence bands x-ray photoemission spectroscopy (XPS) with first-principles density functional theory (DFT) calculations, we demonstrate the Mott Hubbard insulating nature of VCl$_3$ and the existence of electron small 2D magnetic polarons localized on V atom sites by V-Cl bond relaxation. The polarons strongly affect the electromagnetic properties of VCl$_3$ promoting the occupation of dispersion-less spin-polarized V-3d $a_{1g}$ states and band inversion with $e^{'}_{g}$ states. Within the polaronic scenario, it is possible to reconcile different experimental evidences on vanadium trihalides, suggesting that also VI$_3$ hosts polarons. Our results highlight the complex physical behavior of this class of crystals determined by charge trapping, lattice distortions, correlation effects, mixed valence states, and magnetic states.

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Dario Mastrippolito, Luigi Camerano, Hanna Swiatek, Břetislav Šmíd, Tomasz Klimczuk, Luca Ottaviano, Gianni Profeta. 2023-01-16. Polaronic and Mott insulating phase of layered magnetic vanadium trihalide VCl3. https://doi.org/10.1103/physrevb.108.045126

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