Cluster spin-glass ground state in quasi-one-dimensional ${\mathrm{KCr}}_3{\mathrm{As}}_3$

We report structural and physical properties of a new quasi-one-dimensional Cr-based compound, ${\mathrm{KCr}}_3{\mathrm{As}}_3$, which is prepared by potassium deintercalation from the superconductive ${\mathrm{K}}_2{\mathrm{Cr}}_3{\mathrm{As}}_3$. ${\mathrm{KCr}}_3{\mathrm{As}}_3$ adopts the ${\mathrm{TlFe}}_3{\mathrm{Te}}_3$-type structure with space group $P{6}_3/m$ (No. 176). The high-temperature magnetic susceptibility obeys the Curie-Weiss law with an effective magnetic moment of 0.68 ${\mu }_{\mathrm{B}}$/Cr. Below 56 K the susceptibility deviates from the high-temperature Curie-Weiss behavior, coinciding with the rapid increase in resistivity, which suggests formation of spin clusters. The short-range spin correlations are also supported by the specific-heat data. The title material does not exhibit bulk superconductivity; instead, it shows a cluster spin-glass state below $\sim 5$ K.

Figure 1

(a) X-ray diffraction patterns of ${\mathrm{K}}_2{\mathrm{Cr}}_3{\mathrm{As}}_3$ (K233) and ${\mathrm{KCr}}_3{\mathrm{As}}_3$ (K133), indexed with hexagonal lattices. Note that a logarithmic scale is applied for the vertical axis to show possible trace impurities. (b) The Rietveld refinement profile for K133. (c) and (d) depict the [001] projection of the crystal structures of K233 and K133, respectively. Different shades of colors in (c) denote different atomic sites in $z=0$ and $z=0.5$. Nevertheless, the $\left({\mathrm{Cr}}_3{\mathrm{As}}_3\right){}_{\infty }$ chain, which is more clearly shown in the inset of (b), is similar for both materials.

Figure 2

Temperature dependence of resistivity for the ${\mathrm{KCr}}_3{\mathrm{As}}_3$ polycrystalline sample. The inset plots the derivative of resistivity.

Figure 3

(a) Temperature dependence of magnetic susceptibility for ${\mathrm{KCr}}_3{\mathrm{As}}_3$. The dashed lines represent the Curie-Weiss fits. $T_{\chi }^{*}$ marks the onset temperature where the data deviate from the high-temperature Curie-Weiss behavior. (b) Low-temperature magnetic susceptibility with zero-field-cooled (ZFC) and field-cooled (FC) procedures under different external fields. (c) Isothermal magnetizations at different temperatures. The inset shows the low-field data at 2 K. (d) Real part of ac magnetic susceptibility in different oscillating frequencies at zero dc field. The arrows are guides for the eye.

Figure 4

Temperature dependence of specific heat for ${\mathrm{KCr}}_3{\mathrm{As}}_3$, plotted in $C/T$ vs $T^2$. The data of superconducting ${\mathrm{K}}_2{\mathrm{Cr}}_3{\mathrm{As}}_3$ are presented for comparison. The solid red line approximately represents the expected $C/T$ values without the magnetic contribution. The upper inset is an expanded plot for ${\mathrm{KCr}}_3{\mathrm{As}}_3$, in which an anomaly owing to trace superconducting transition is marked. The lower inset shows the $C\left(T\right)$ data in a broad temperature range.