Figure 1

Left: Schematic phase diagram of ${\mathrm{YbRh}}_2{\mathrm{Si}}_2$ for $B\perp c$ from Ref. 1. Dashed and solid gray lines delineate the region of heavy QP behavior confined to the region $T<T_0$ and $B<B^{*}$ [2, 4, 5]. The LFL region denotes the $T\mathrm{\text{−}}B$ domain where the resistivity follows LFL behavior $\rho \propto T^2$. The broad (pink online) line $T^{*}$ depicts the position of crossover in the isothermal Hall resistance, magnetostriction, magnetization, and longitudinal resistivity. Closed symbols depict $T(B)$-crossover temperatures below which specific heat ($\gamma$) [2] and ${}^{29}\mathrm{Si}\mathrm{\text{−}}\mathrm{NMR}$ quantities [$K$ and $1/(T_{1}T)$] [3] become $T$ independent. Open symbols display crossover temperatures from HF ESR $g(T,B)$ and $\Delta B(T,B)$ dependences (see text). Right: A representative HF ESR signal for the $B\perp c$ axis. Absorptive (amplitude) and dispersive (phase shift) parts of the ESR signal (noisy curves) are simultaneously fitted to a Lorentzian function (solid lines). No signal can be observed for the $B\parallel c$ axis, suggesting a strong $g$ factor anisotropy.Reuse & Permissions

Figure 2

(a) $g(T)$ dependence for $B\perp c$ at $\nu =9$, 34, 93, 249, 297, and 360 GHz (from bottom to top), which correspond to resonance fields as indicated. Arrows indicate a crossover from a $-\ln T$ to $g=\mathrm{const}$ behavior. (b) $T$ dependence of the Sommerfeld coefficient $\gamma$ at different magnetic fields (Ref. 5). (c) Field dependence of low temperature $\gamma$ (Ref. 5) and $g$ shift between 20 K and 2 K.Reuse & Permissions

Figure 3

(a) $T$ dependence of the linewidth $\Delta B$ for $B\perp c$ at $\nu =93$ (squares), 249 (diamonds), 297 (triangles), and 360 GHz (circles). Solid lines are fits (see the text). (b) Corresponding low-$T$ data in the representation $\Delta B$ vs $T^2$. Solid lines are fits to the $T^2$ dependence. (c) $T$ dependence of ${}^{29}\mathrm{Si}$ relaxation rate $1/(T_{1}T)$ from Ref. 3.Reuse & Permissions