Magnetic-field tuning of the low-temperature state of $\mathrm{Yb}\mathrm{Ni}{\mathrm{Si}}_3$

We present detailed data from low-temperature magnetization, magnetoresistance, and specific heat measurements on single-crystal $\mathrm{Yb}\mathrm{Ni}{\mathrm{Si}}_3$ with the magnetic field applied along the easy magnetic axis, $H\Vert b$. An initially antiferromagnetic ground state changes into a field-stabilized metamagnetic phase at $\sim 16\mathrm{kOe}$ $(T\to 0)$. On further increase of the magnetic field, magnetic order is suppressed at $\sim 85\mathrm{kOe}$. No non-Fermi-liquid-like power law was observed in the resistivity in the vicinity of the critical field for $T⩾0.4\mathrm{K}$. Heat capacity measurements suggest that the applied magnetic field splits the nearly degenerate crystal-electric-field levels that form the zero-field ground state of $\mathrm{Yb}\mathrm{Ni}{\mathrm{Si}}_3$. The functional behaviors of the resistivity and specific heat are discussed in comparison with those of the few other stoichiometric heavy fermion compounds with established field-induced quantum critical points.

Figure 1

Low-temperature dc magnetic susceptibility, $M\left(T\right)∕H$, measured in $\mathrm{Yb}\mathrm{Ni}{\mathrm{Si}}_3$ in different applied fields, $H\Vert b$. Inset: $d\left(\chi T\right)∕dT$ corresponding to the data in the main panel. Gap in the data near between 4.3 and $4.6\mathrm{K}$ corresponds to the region of unstable temperature control in our MPMS-5 magnetometer.

Figure 2

Representative magnetic isotherms, $M\left(H\right)$, measured in $\mathrm{Yb}\mathrm{Ni}{\mathrm{Si}}_3$ at different temperatures for $H\Vert b$. Insets: enlarged low- and high-field plots of corresponding $dM∕dH$. Arrows on the upper left inset mark the second high-field feature, which broadens beyond the resolution for $T=5\mathrm{K}$.

Figure 3

Low-temperature resistivity isotherms, $\rho \left(H\right)$, measured at (from the bottom to the top) 0.4, 0.76, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, and $4\mathrm{K}$. Dashed lines are guide for the eye.

Figure 4

Representative low-temperature resistivity curves measured in zero and applied magnetic fields. Curves are shifted down along the $Y$ axis by multiples of $5\mu \Omega \mathrm{cm}$ for clarity. Numbers correspond to the applied field in kOe.

Figure 5

Low-temperature heat capacity, $C_p\left(T\right)$, measured in different applied magnetic fields. Inset of panel (b): $C_p∕T$ as a function of temperature. Note that the curve for $H=70\mathrm{kOe}$ is shown on both panels.

Figure 6

Heat capacity in applied field for $70⩽H⩽140\mathrm{kOe}$ plotted as $C_p∕T$ vs $T^2$. Dashed line—linear extrapolation from the high-temperature data. Insets: left—enlarged low-temperature part and right—estimate of $\gamma$ from the extrapolated low-temperature linear portion of the $C_p∕T$ vs $T^2$ graph.

Figure 7

$H\text{−}T$ phase diagram of $\mathrm{Yb}\mathrm{Ni}{\mathrm{Si}}_3$ for $H\Vert b$. Different symbols correspond to the phase lines obtained from different thermodynamic and transport measurements: open circle—$M\left(T\right)$, filled circle—$M\left(H\right)$, open star—$C_p\left(T\right)$, filled star—$\rho \left(T\right)$, and diamond and asterisk—$\rho \left(H\right)$. Crosses correspond to the position of broad maxima in $C_p∕T$ and dashed lines are guides for the eye.

Figure 8

(Color online) Results of fitting of low-temperature resistivity to the form $\rho \left(T\right)={\rho }_0+A{T}^{\beta }$; units of $\rho \left(T\right)$ and ${\rho }_0$ are in $\mu \Omega \mathrm{cm}$. Circles: fit from $3\mathrm{K}$ to the base temperature and triangles: fit from $1.5\mathrm{K}$ to the base temperature. Nominal error bars of the fits are shown. Vertical dashed lines mark $T\to 0$ critical fields from the phase diagram above.