nuclear quadrupole resonance as a microscopic probe in the Te-doped correlated semimetal : Emergence of electronic Griffith phase, magnetism, and metallic behavior
- Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); M.V. Lomonosov Moscow State University (Russia). Faculty of Physics
- M.V. Lomonosov Moscow State University (Russia). Faculty of Physics
- Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Department
- Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)
121,123Sb nuclear quadrupole resonance (NQR) was applied to Fe(Sb1-xTex)2 in the low doping regime (x = 0 , 0.01, and 0.05) as a microscopic zero field probe to study the evolution of 3d magnetism and the emergence of metallic behavior. Whereas the NQR spectra itself reflects the degree of local disorder via the width of the individual NQR lines, the spin lattice relaxation rate (SLRR) 1/T1 (T) probes the fluctuations at the Sb site. The fluctuations originate either from conduction electrons or from magnetic moments. In contrast to the semimetal FeSb2 with a clear signature of the charge and spin gap formation in 1/T1(T)T[~exp/(ΔkBT)] , the 1% Te-doped system exhibits almost metallic conductivity and the SLRR nicely confirms that the gap is almost filled. A weak divergence of the SLRR coefficient 1/T1(T)T ~ T-n ~ T-0.2 points towards the presence of electronic correlations towards low temperatures. This is supported by the electronic specific heat coefficient γ = (Cel/T) showing a power-law divergence γ (T) ~ T-m ~ (1/T1T)1/2 ~ T-n/2 ~ Cel/T which is expected in the renormalized Landau Fermi liquid theory for correlated electrons. In contrast to that the 5% Te-doped sample exhibits a much larger divergence in the SLRR coefficient showing 1/T1(T)T ~ T-0.72 . According to the specific heat divergence a power law with n = 2 m = 0.56 is expected for the SLRR. This dissimilarity originates from admixed critical magnetic fluctuations in the vicinity of antiferromagnetic long range order with 1/T1(T)T ~ T-3/4 behavior. Furthermore Te-doped FeSb2 as a disordered paramagnetic metal might be a platform for the electronic Griffith phase scenario. NQR evidences a substantial asymmetric broadening of the 121,123Sb NQR spectrum for the 5% sample. Lastly, this has a predominant electronic origin in agreement with the electronic Griffith phase and stems probably from an enhanced Sb-Te bond polarization and electronic density shift towards the Te atom inside Sb-Te dumbbell.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0012704
- OSTI ID:
- 1430876
- Alternate ID(s):
- OSTI ID: 1420201
- Report Number(s):
- BNL-203432-2018-JAAM; PRBMDO; TRN: US1802629
- Journal Information:
- Physical Review B, Vol. 97, Issue 7; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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