Continuous Evolution of the Fermi Surface of ${\mathrm{CeRu}}_2{\mathrm{Si}}_2$ across the Metamagnetic Transition

We present new, high resolution Hall effect and magnetoresistance measurements across the metamagnetic transition in the heavy fermion compound ${\mathrm{CeRu}}_2{\mathrm{Si}}_2$. The results, and ambiguities in the interpretation of de Haas–van Alphen data, force us to rethink the notion that the transition is accompanied by an abrupt $f$-electron localization. Instead, we explain our data assuming a continuous evolution of the Fermi surface, which sees one of the spin-split sheets of the heaviest surface shrink to a point.

Figure 1

In-plane ($ȷ\parallel ab$, $B\parallel c$) transverse magnetoresistivity (${\rho }_{xx}$, upper panel) and Hall effect (${\rho }_{xy}$, lower panel) for ${\mathrm{CeRu}}_2{\mathrm{Si}}_2$. The base $T$ is around 6.5 mK.

Figure 2

$T$-dependent resistivity at a few fixed values of $B$ (inset), and density plot of the power law exponent $x$ versus $B$ and $T$ (main panel), interpolated from $T$ sweeps at $B=0.2$, 2, 4, 5.5, 6.5, 7.3, 7.7, 8, 8.3, 8.7, 9.5, 10.5, 12, 14, and 16 T.

Figure 3

Magnetoresistivity and Hall resistivity of a model system consisting of a spin-split, holelike spherical Fermi surface where one of the spin sheets shrinks to a point at $B_{\mathrm{MMT}}$. The pictures show the field evolution of the Fermi surface.

Figure 4

The $\mu$ orbit in the $f$-band calculation (left, centered on $\Gamma$) and $\omega$ orbit in the $f$-core calculation (right, centered on Z) in ${\mathrm{CeRu}}_2{\mathrm{Si}}_2$ [25] have very similar on-axis dHvA frequencies, around 28 kT. Figure adapted from Ref. 26.