Breakdown of the coherence effects and Fermi liquid behavior in YbAl₃nanoparticles

Abstract

A change in the Kondo lattice behavior of bulk YbAl has been observed when the alloy is shaped into nanoparticles (≈12 nm). Measurements of the electrical resistivity show inhibited coherence effects and deviation from the standard Fermi liquid behavior (T -dependence). These results are interpreted as being due to the effect of the disruption of the periodicity of the array of Kondo ions provoked by the size reduction process. Additionally, the ensemble of randomly placed nanoparticles also triggers an extra source of electronic scattering at very low temperatures (≈15 K) due to quantum interference effects.

Negative Thermal Expansion in Nanostructured Intermediate-Valence YbAl3

“…In order to provide a more accurate value of T K , quasielastic neutron scattering experiments should be performed. This result is in good agreement with the increase of the Debye temperature found in the thermal expansion behavior above that also indicated a T K enhancement, modifying the coherence effects at low temperatures, as reported in previous results of milled YbAl 3 alloys [Echevarria-Bonet 2018]. The behavior of the curves here is in good agreement with those in the literature [Rojas 2008] for milled YbAl 3 alloys though T max values are slightly different.…”

“…These results are interpreted as being due to the effect of the disruption of the periodicity of the array of Kondo ions provoked by the size reduction process [Echevarria-Bonet 2018]. Coherence effects in bulk YbAl 3 [Bauer 2004] are modified in nanostructures of this alloy [Echevarria-Bonet 2018]. In this sense, Yb 1−x Lu x Al 3 series of bulk alloys have been also studied, and changes in specific heat, susceptibility, and electrical resistivity were found, suggesting that coherence effects are very sensitive to lattice order [Ebihara 2003].…”

“…Measurements of the electrical resistivity show inhibited coherence effects and deviation from the standard Fermi liquid behavior (T 2 dependence). These results are interpreted as being due to the effect of the disruption of the periodicity of the array of Kondo ions provoked by the size reduction process [Echevarria-Bonet 2018]. Coherence effects in bulk YbAl 3 [Bauer 2004] are modified in nanostructures of this alloy [Echevarria-Bonet 2018].…”

Emergent Coherent Lattice Behavior in Kondo Nanosystems

“…Starting from an incoherent dilute limit of Kondo impurities, one possibility to study how the lattice effects come into play is to increase the concentration of magnetic ions [28][29][30][31][32][33][34][35]. However, the electronic structure of bulk HF materials is essentially three dimensional, and one may wonder how the coherence phenomena are affected either by reduced dimensionality or in spatially restricted geometries where both quantum fluctuations and correlations effect are enhanced [36,37]. In this respect, the experimental realization of artificial f -electron superlattices [38] has opened a new avenue to investigate the onset of coherence in a two-dimensional (2D) regime followed up by theoretical studies [39].…”