Phase diagram of CeVSb${}_3$ under pressure and its dependence on pressure conditions

We present temperature dependent resistivity and ac-calorimetry measurements of CeVSb${}_3$ under pressure up to 8 GPa in a Bridgman anvil cell modified to use a liquid medium and in a diamond anvil cell using argon as a pressure medium. An initial increase of the ferromagnetic transition temperature $T_C$ with pressures up to 4.5 GPa is observed, followed by decrease of $T_C$ on further increase of pressure and finally its disappearance, in agreement with the Doniach model. We infer a ferromagnetic quantum phase transition around 7 GPa under hydrostatic pressure conditions from the extrapolation to 0 K of $T_C$ and the maximum of the A coefficient from low temperature fits of the resistivity $\rho \left(T\right)={\rho }_0+A{T}^n$. No superconductivity under pressure was observed down to 0.35 K for this compound. In addition, differences in the $T_C$(P) behavior when a slight uniaxial component is present are noticed and are correlated to the choice of pressure medium.

Figure 1

(a) Resistivity, at ambient pressure, of CeVSb${}_3$ along the b and c axes. The resistivity along the third direction is added to the two other in the inset. (b) Anisotropic thermal expansion coefficients of CeVSb${}_3$; inset shows expanded, low temperature range.

Figure 2

Resistivity measurement of CeVSb${}_3$ under pressure. Sketches illustrate the sample orientations in the pressure cells. Insets: low temperature resistivity. (a) with current along the c axis and pressure applied along the a axis. (b) with current along the c axis and pressure applied along the b axis. (c) with current along the b axis and pressure applied along the c axis.

Figure 3

Resistivity derivative $d\rho \left(T\right)/dT$ of CeVSb${}_3$ under pressure. Sketches outline the sample orientations in the pressure cells. (a) with current along the c axis and pressure applied along the a axis in a cell filled with 1:1 n-pentane:isopentane (in $\mu \Omega$ cm/K) at 0 GPa and arbitrary units under pressure). (b) with the same orientation, but filled with 1:1 FC70:FC77 (c) with current along the c axis and pressure applied along the b axis with 1:1 FC70:FC77 as a pressure medium. (d) with current along the b axis and pressure applied along the c axis with 1:1 FC70:FC77 as a pressure medium.

Figure 4

Specific heat of CeVSb${}_3$ (in arbitrary units) under pressure, measured in the diamond anvil cell. Pressures are given in GPa.

Figure 5

T(P) phase diagram of CeVSb${}_3$. We added data from magnetization measurements performed in a piston-cylinder cell.[1] For a given symbol, experimental conditions were similar, and the different colors refer to different runs. (a) Comparison between the different axis orientations in the Bridgman anvil cell. Diamond anvil cell $C_P$ data points are also shown. Crosses are the lowest measured temperature for the lowest pressure for which no phase transition could be detected. $P_1$, $P_2$, $P_3$, and $P_4$ are given by downward arrows and refer to the critical pressures estimated from Fig. 8. (b) Comparison between the different pressure media used.

Figure 6

Evolution with pressure of the difference in temperature between two criteria for the magnetic transition. Several curves are shown for different resistivity measurement conditions and one for the specific heat. Three data sets are shown for P//a (stars). The inset shows the definition for these two criteria, for the resistivity derivative and the specific heat.

Figure 7

Resistivity of CeVSb${}_3$ with the residual resistivity subtracted for each pressure. A logarithmic scale is used for this plot. Linear fits at low temperature are shown for each pressure. This set of data was already shown in Fig. 2a.

Figure 8

Pressure dependence of the parameters obtained from a low temperature fit $\rho \left(T\right)={\rho }_0+A{T}^n$. The arrows labeled $P_1$, $P_2$, $P_3$, and $P_4$ are the estimated critical pressures (see text) from runs performed using the Fluorinert medium, ${\rho }_{c,P//a}$ for $P_1$ and $P_2$ (with the same experimental conditions to check for reproducibility), ${\rho }_{c,P//b}$ for $P_3$ and ${\rho }_{b,P//c}$ for $P_4$. The triangles refer to fits down to ${}^3$He temperatures. The colors are chosen the same as in Fig. 5a. A coefficient. (b) Temperature exponent, n. (c) Residual resistivity, ${\rho }_0$.

Figure 9

Pressure dependence of the parameters obtained from a low temperature fit $\rho \left(T\right)={\rho }_0+A{T}^2$ from ${}^3$He data of ${\rho }_{c,P//a}$. (a) A coefficient. The inset shows the maximum temperature where this fit applies. (b) Residual resistivity, ${\rho }_0$.

Figure 10

Dependence on a scaled pressure of the parameters obtained from a low temperature fit $\rho \left(T\right)={\rho }_0+A{T}^n$ ($T⩾$1.8 K). The critical pressure values, $P_c$, used here were given in the results section from the low temperature fits of the resistivity. (a) A coefficient. (b) Temperature exponent, n.