Two-Channel Kondo Lattice: An Incoherent Metal

Abstract

The paramagnetic phase of the two-channel Kondo lattice model is examined with a quantum Monte Carlo simulation in the limit of infinite dimensions. We find non-Fermi-liquid behavior at low temperatures including a finite low-temperature single-particle scattering rate, no Fermi distribution discontinuity, and zero Drude weight. However, the low-energy density of electronic states is finite. We label our model system in this phase an "incoherent metal." We discuss the relevance of our results for concentrated heavy fermion metals with non-Fermi-liquid behavior. [S0031-9007(96) The Fermi liquid theory of Landau has provided a remarkably robust paradigm for describing the properties of interacting fermion systems such as liquid 3 He and alkali metals (e.g., sodium). The key notion of this theory is that the low lying excitations of the interacting system possess a 1:1 map to those of the noninteracting system and hence are called "quasiparticles." In the metallic context, one may think of the quasiparticles as propagating electronlike wave packets with renormalized magnetic moment and effective mass reflecting the "molecular field" of the surrounding medium. A sharp Fermi surface remains in the electron occupancy function n k which measures the number of electrons with a given momentum, and for energies v and temperatures T asymptotically close to the Fermi surface the excitations have a decay rate going as v 2 1 p 2 ͑k B T͒ 2 , which is much smaller than the quasiparticle energy, and generally translates into a T 2 contribution to the electrical resistivity r͑T ͒. This theory has proven useful in describing phase transitions within the Fermi liquid, such as superconductivity which is viewed as a pairing of Landau quasiparticles in conventional metals such as aluminum.The Fermi liquid paradigm appears now to be breaking down empirically in numerous materials, notably the quasi-two-dimensional cuprate superconductors [1] and a number of fully three-dimensional heavy Fermion alloys and compounds [2]. In these systems such anomalies as a conductivity with linear dependence on v, T and logarithmically divergent linear specific heat coefficients are often observed. If the quasiparticle paradigm indeed breaks down, this may require completely new concepts to explain the superconducting phases of these materials. While the Luttinger liquid theory provides an elegant way to achieve non-Fermi-liquid theory in one dimension (with, e.g., no jump discontinuity in n k , and separation or unbinding of spin and charge quantum numbers), this results from the special point character of the Fermi surface. Whether the essential spin-charge separation may "bootstrap" into higher dimensions remains unclear [3].Among the remaining theories to explain experiment are those based upon proximity to a zero-temperature quantum critical point [4], those based upon disorder induced distributions of Kondo scales in local moment systems [5], and those which hope to explain the physics from impurity to lattice crossover effects in the multichanne...

Spin Density Wave Driven by Quadrupolar Kondo Effect in Two-Channel Kondo Lattice

“…Mathematically speaking, the present model has the same energy levels as those in the previous model [5][6][7] where each localized spin (Kramers doublet) interacts magnetically with conduction electrons distributing in two bands. If one interchanges the orbital and spin degrees of freedom, our model is reduced to that in refs.…”

“…1) For the periodic system, on the other hand, the two-channel Kondo lattice model (2ch KLM) has been investigated in the region near the half filling of conduction electrons. 5,6) Detailed properties of the 2ch KLM remain to be clarified especially away from the half filling. In one dimension, the ground state phase diagram of the 2ch KLM has been proposed by the density matrix renormalization group.…”

Quantum effects in the quasiparticle structure of the ferromagnetic Kondo lattice model

“…This approach is, however limited to S = 1 2 systems (see also [52,53,54]). The first part of our approach will closely follow Ref.…”

Magnetic ordering and non-Fermi-liquid behavior in the multichannel Kondo-lattice model

“…The model permits a consistent scaling investigation since the fixed point is within the weak-coupling region (however, the marginal case M = 2 has some peculiarities). On the other hand, the lattice case is more difficult and only special approaches, in particular for one-dimensional models [8,12] and infinite space dimension [13] were used. In the present paper we start from the standard microscopic model of a periodical Kondo lattice and treat the interplay of the on-site Kondo screening and intersite exchange interactions within a scaling approach.…”