Itinerant Versus Localized Heavy-Electron Magnetism

The nature of the itinerant-localized transition of heavy electrons is clarified for the Kondo-Heisenberg lattice at finite temperatures. The phase diagram and electronic structure are derived by means of the continuous-time quantum Monte Carlo method combined with the dynamical mean-field theory. Around the itinerant-localized transition inside the antiferromagnetic phase, nearly flat bands appear on the Fermi surface with an almost vanishing quasiparticle renormalization factor. At the same time, there emerges a strong local magnetic fluctuation with a minute energy scale. Considering both antiferromagnetic and ferromagnetic Heisenberg interactions, a coherent understanding is achieved on rich phase diagrams observed in ${\mathrm{CeRh}}_{1-x}{\mathrm{Co}}_x{\mathrm{In}}_5$, ${\mathrm{CeRu}}_2({\mathrm{Si}}_x{\mathrm{Ge}}_{1-x}{)}_2$, ${\mathrm{UGe}}_2$, and $\mathrm{Ce}{T}_2{\mathrm{Al}}_{10}$ ($T=\mathrm{Fe}$, Ru, Os).

Figure 1

Temperature dependence of the electrical resistivity for $J_{\mathrm{K}}\ge 0.2$. The dotted arrow shows the change of $T_{\mathrm{F}}^{*}$ with decreasing $J_{\mathrm{K}}$.

Figure 2

(a) Temperature ($T$) versus Kondo interaction ($J_{\mathrm{K}}$) phase diagram for $J_{\mathrm{H}}=0.025$. The $J_{\mathrm{K}}$ dependences of the (b) magnetic moment, (c) renormalization factors, and (d) local magnetic susceptibility are also shown.

Figure 3

Single-particle spectrum $A_{\sigma }({\epsilon }_{\mathit{k}},E)$ at $T=0.0025$ for (a) $J_{\mathrm{K}}=0.125$ and (b) $J_{\mathrm{K}}=0.225$. The insets in (a),(b) show the schematic illustrations for spectra in the localized (AFM) and itinerant (Para) limits, respectively.

Figure 4

Phase diagram of the Kondo-Heisenberg lattice in the $J_{\mathrm{H}}\mathrm{\text{−}}{J}_{\mathrm{K}}$ plane at $T=0.001$. The abbreviations $L$ and $I$ mean localized and itinerant, respectively. At the critical value $J_{\mathrm{K}}=J_{c2}$ for the ILT; the corresponding $J_{\mathrm{H}}$ mostly scales with the Kondo temperature $T_{\mathrm{K}}$.