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Title: Hybridization gap and dual nature of the heavy-fermion compound UPd 2Al 3 via quasiparticle scattering spectroscopy

We present results from point-contact spectroscopy of the antiferromagnetic heavy-fermion superconductor UPd 2Al 3 : Conductance spectra are taken from single crystals with two major surface orientations as a function of temperature and magnetic field and analyzed using a theory of cotunneling into an Anderson lattice. Spectroscopic signatures are clearly identified, including the distinct asymmetric double-peak structure arising from the opening of a hybridization gap when a coherent heavy-Fermi liquid is formed. Both the hybridization gap, found to be 7.2 ± 0.3 meV at 4 K, and the conductance enhancement above a flat background decrease upon increasing temperature. While the hybridization gap is extrapolated to remain finite up to ~28 K, close to the temperature around which the magnetic susceptibility displays a broad peak, the conductance enhancement vanishes at ~18 K, slightly above the antiferromagnetic transition temperature (T N ≈ 14 K) . This rapid decrease of the conductance enhancement is understood as a consequence of the junction drifting away from the ballistic regime due to increased scattering off magnons associated with the localized U 5 f electrons. This shows that while the hybridization gap opening is not directly associated with the antiferromagnetic ordering, its visibility in the conductance ismore » greatly affected by the temperature-dependent magnetic excitations. Our findings are not only consistent with the 5 f dual-nature picture in the literature but also shed new light on the interplay between the itinerant and localized electrons in UPd 2Al 3 .« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [3] ; ORCiD logo [3] ; ORCiD logo [3] ; ORCiD logo [3] ;  [2]
  1. Illinois Wesleyan Univ., Bloomington, IL (United States); Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Physics and Materials Research Lab.
  2. Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Physics and Materials Research Lab.
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-16-28194
Journal ID: ISSN 2469-9950; TRN: US1702655
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 95; Journal Issue: 16; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC). Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1369187
Alternate Identifier(s):
OSTI ID: 1351928