Crystal growth, structure and physical properties of quasi-one-dimensional tellurides Fe${}_{4-x}$VTe${}_{4-y}$ ($x=1.01$, $y=0.74$) and V${}_{4.64}$Te${}_4$

Abstract

A new ternary compound Fe${}_{4-x}$VTe${}_{4-y}$ ($x=1.01$, $y=0.74$) with Ti5Te4-type structure is identified. Fe and V atoms tend to occupy different crystallographic positions and form quasi-one-dimensional (quasi-1D) Fe-V chains along the c-axis. Millimeter-sized single crystal of Fe${}_{2.99}$VTe${}_{3.26}$ (FVT) with slender-stick shape could be grown by chemical vapor transport method which reflects its quasi-1D crystal structure. Magnetization measurements reveal that FVT orders antiferromagnetically below T${}_N$=93 K with strong easy ab-plane magnetic anisotropy. Although a weak glassy-like behavior appears below 10 K, FVT is dominant by long-range antiferromagnetic order in contrast to the spin-glass state in previously reported isostructural Fe${}_5$Te${}_4$. We also synthesize V${}_{4.64}$Te${}_4$ with similar quasi-1D V-chains and find it has weak anomalies at 144 K on both resistivity and susceptibility curves. However, no clear evidence is found for the development of magnetic or charge order. X-ray photoelectron spectroscopy and Curie-Weiss fit reveal that the effective moments for Fe${}^{2+}$ and V${}^{4+}$ in both compounds have large deviations from the conventional local moment model, which may possibly result from the formation of Fe/V metal-metal bondings. Furthermore the resistivity of both FVT and V${}_{4.64}$Te${}_4$ exhibits semiconducting-like temperature-dependent behavior but with average values close to typical bad metals, which resembles the transport behavior in the normal state of Fe-based superconductors. These quasi-1D compounds have shown interesting physical properties for future condensed matter physics research.

19 pages, 5 figures