Magnetic ordering in frustrated ${\mathrm{Ce}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$

The transport, magnetic, and thermal properties are studied on an antiferromagnetic compound ${\mathrm{Ce}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$ with $T_N=7.3\mathrm{K}$. We find signatures of spin fluctuation in this geometrically frustrated magnet. The Curie-Weiss fit gives a large value of the paramagnetic Curie temperature, yielding a frustration parameter $f=8.4$. The electronic specific heat coefficient $\gamma =300\mathrm{mJ}∕\mathrm{Ce}\mathrm{mol}{\mathrm{K}}^2$ is strongly enhanced, leading to residual entropy at low temperatures. The spin fluctuation is suppressed as the magnetic field exceeds the metamagnetic transition field $H_m=1\mathrm{T}$, where the magnetoresistance decreases steeply. The steady increase of magnetic susceptibility below $T_N$ is likely to be associated with the presence of paramagnetic Ce ions. For ${\mathrm{La}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$, a superconducting transition is observed at $T_c=1.8\mathrm{K}$.

Figure 1

Perspective (upper panel) (Ref. 7) and projective (lower panel) views of unit cell for ${\mathrm{Ce}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$. Ce atoms are represented by large gray and black circles, which are in the $c∕4$ and $3c∕4$ sites, respectively. Ni atoms are small black and Si atoms are small gray.

Figure 2

(Color) (a) Magnetic contribution $C_m\left(T\right)$ to the specific heat and (b) $C_m∕T$ of ${\mathrm{Ce}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$ in various magnetic fields. Temperature dependence of the magnetic entropy $S_m\left(T\right)$ is plotted in the inset.

Figure 3

(a) Temperature dependence of the magnetic susceptibility $\chi \left(T\right)$ and its inverse $1∕\chi \left(T\right)$ for ${\mathrm{Ce}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$ measured at $H=100\mathrm{G}$. The inset shows the low temperature data of $\chi \left(T\right)$. (b) Temperature dependence of the electrical resistivity $\rho \left(T\right)$ for ${\mathrm{Ce}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$ and ${\mathrm{La}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$. The resistivity of ${\mathrm{La}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$ shifts to a positive direction by $70\mu \Omega \mathrm{cm}$. The magnetic contribution ${\rho }_m$ to the electrical resistivity of ${\mathrm{Ce}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$ is also plotted. The inset shows the low temperature data of ${\rho }_m$.

Figure 4

(Color) Temperature dependence of the electrical resistivity $\rho \left(T\right)$ measured at various magnetic fields for ${\mathrm{Ce}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$.

Figure 5

(Color) (a) Magnetic field dependence of the electrical resistivity $\rho \left(H\right)$. The field derivatives of the electrical resistivity $\mathrm{d}\rho ∕\mathrm{d}H$ at various temperatures are plotted in the inset. (b) Magnetic field dependence of the magnetization $M\left(H\right)$ and the field derivative $\mathrm{d}M∕\mathrm{d}H$ at $T=2\mathrm{K}$ for ${\mathrm{Ce}}_5{\mathrm{Ni}}_2{\mathrm{Si}}_3$.