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Competing 4 f-electron dynamics in Ce(Ru1-xFex)(2)Al-10 (0

In English

Författare

  • D. T. Adroja
  • A. D. Hillier
  • Y. Muro
  • J. Kajino
  • T. Takabatake
  • P. Peratheepan
  • A. M. Strydom
  • Pascale Deen
  • F. Demmel
  • J. R. Stewart
  • J. W. Taylor
  • R. I. Smith
  • S. Ramos
  • M. A. Adams
Visa allt

Summary, in English

We have carried out muon spin relaxation (mu SR), neutron diffraction, and inelastic neutron scattering (INS) investigations on polycrystalline samples of Ce(Ru1-xFex)(2)Al-10 (x = 0, 0.3, 0.5, 0.8, and 1) to investigate the nature of the ground state (magnetic ordered versus paramagnetic) and the origin of the spin-gap formation as evident from the bulk measurements in the end members. Our zero-field mu SR spectra clearly reveal coherent two-frequency oscillations at low temperature in x = 0, 0.3, and 0.5 samples, which confirm the long-range magnetic ordering of the Ce moment with Neel temperature T-N = 27, 26, and 21 K, respectively. On the other hand, the mu SR spectra of x = 0.8 and x = 1 down to 1.4 K and 0.045 K, respectively, exhibit a temperature-independent Kubo-Toyabe term, confirming a paramagnetic ground state. The long-range magnetic ordering in x = 0.5 below 21 K has been confirmed through the neutron diffraction study. INS measurements of x = 0 clearly reveal the presence of a sharp inelastic excitation near 8 meV between 5 K and 26 K, due to an opening of a gap in the spin excitation spectrum, which transforms into a broad response at and above 30 K. Interestingly, at 4.5 K, the spin-gap excitation broadens in x = 0.3 and exhibits two clear peaks at 8.4(3) and 12.0(5) meV in x = 0.5. In the x = 0.8 sample, which remains paramagnetic down to 1.2 K, there is a clear signature of a spin gap of 10-12 meV at 7 K, with a strong wave-vector-dependent intensity. Evidence of a spin gap of 12.5(5) meV has also been found in x = 1. The observation of a spin gap in the paramagnetic samples (x = 0.8 and 1) is an interesting finding in this study, and it challenges our understanding of the origin of the semiconducting gap in CeT2Al10 (T = Ru and Os) compounds in terms of a hybridization gap opening only a small part of the Fermi surface, gapped spin waves, or a spin-dimer gap.

Publiceringsår

2013

Språk

Engelska

Publikation/Tidskrift/Serie

Physical Review B (Condensed Matter and Materials Physics)

Volym

87

Issue

22

Dokumenttyp

Artikel i tidskrift

Förlag

American Physical Society

Ämne

  • Physical Sciences
  • Natural Sciences

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1098-0121