Premium
Quenching of spin fluctuations in the 3d and 4f aluminides YFe 2 Al 10 and YbFe 2 Al 10 : a comparative 27 Al NMR and specific heat study
Author(s) -
Khuntia P.,
Strydom A.,
Steglich F.,
Baenitz M.
Publication year - 2013
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201200758
Subject(s) - isostructural , condensed matter physics , quantum critical point , ferromagnetism , valence (chemistry) , physics , lattice (music) , quantum fluctuation , spin (aerodynamics) , magnetic susceptibility , materials science , phase transition , chemistry , quantum , quantum phase transition , crystal structure , thermodynamics , crystallography , quantum mechanics , acoustics
Abstract We present investigations on the magnetic susceptibility χ ( T ), the specific heat coefficient γ ( T ) = C ( T )/ T , and the spin‐lattice relaxation (SLR) rate on the two isostructural iron aluminides YFe 2 Al 10 and YbFe 2 Al 10 . Below 10 K, both systems display a monotonous field‐dependent increase with decreasing temperature in χ ( T ), γ ( T ) and the SLR coefficient 27 R ( T ) = 27 (1/ T 1 T ). These divergences are associated with spin fluctuations near a quantum critical point (QCP). Most probably, the QCP is of ferromagnetic (FM) nature, but so far no magnetic order is observed in either system down to 0.35 K. The application of moderate fields of a few Tesla suppresses the low‐ T upturn in the properties. The comparison between zero‐field and high field measurements allow for the determination of enhancement factors in χ ( T ), the γ ( T ), and the spin‐lattice relaxation coefficient (SLRC) 27 R ( T ). Surprisingly, the relative enhancement in γ ( T ) and the T ‐dependence [∝ ln(1/ T )] are very similar for both systems. In the SLRC, the enhancement is larger for the Yb‐system but both show ln(1/ T ) behavior for T → 0. The divergences are very similar because the Yb ions in YbFe 2 Al 10 are in an intermediate valence state at low temperatures and contribute only very little towards the observed spin fluctuations. This indicates strongly the same underlying physics and the same energy scales for both systems. We propose the presence of dominant q = 0 low‐energy FM spin fluctuations from weak itinerant Fe as the origin for the observed logarithmic divergences.