Itinerant Versus Localized Heavy-Electron Magnetism

Abstract

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 CeRh(1-x)Co(x)In5, CeRu2(Si(x)Ge(1-x))2, UGe2, and CeT2Al10 (T=Fe, Ru, Os).

Fermi Surface Properties, Metamagnetic Transition and Quantum Phase Transition of CeRu2Si2 and Its Alloys Probed by the dHvA Effect

“…The dHvA signal intensity with fields parallel to the [100] direction is mostly smaller than that with fields parallel to the [110] direction. However, we could observe rather clear signals of the α 1 , α 2 and α 3 oscillations for x around 0.5 -0.6.…”

“…In §3. The oscillation which is probably attributed to the µ orbit in Fig with tilting the field direction from [100] to [110].…”

“…100 By using a similar model, we conjecture that the change of the phase diagram with x comes from the change in the relative strengths of the interactions as follows. We denote the strengths of the antiferromagnetic interaction, the ferromagnetic interaction, and although no ferromagnetic order is present.…”

“…Figure 39 shows the amplitudes of the ω oscillation as a function of temperature for the fields parallel to the [100] direction and for the fields tilted by 10 degrees from the [100] and do not change with temperature. On the other hand, for fields parallel to the [100] direction, the data point curve has a structure which cannot be fitted by a single curve given by eq. (A·15) or eq.(A·21).…”

Summary of SCES2013: Theoretical Aspects

“…Microscopic calculation at zero magnetic field has shown [17] that a behavior reminiscent of quantum criticality appears provided the first-order Lifshitz-type transition is small.…”