Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 59: Correlated Electrons: Quantum-Critical Phenomena - Experiments
TT 59.11: Vortrag
Donnerstag, 14. März 2013, 18:00–18:15, H6
NMR as a local probe for ferromagnetic correlation and quantum criticality in 3d systems: YFe2Al10 and Ta(Fe1−xVx)2 — •P. Khuntia1, M. Brando1, A. Strydom2, M. Aronson3, G. Kreiner1, F. Steglich1, and M. Baenitz1 — 1Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany — 2Physics Department, University of Johannesburg,South Africa — 3Brookhaven National Laboratory, New York 11973, USA
Probing the q-averaged dynamic
susceptibility at low energies, the spin lattice relaxation rate by T, (1/T1T)
(SLR) is ideal for the investigation of FM and AFM
spin fluctuations. At the verge of magnetic order, unusual scaling
laws in T and H dependent SLR could be associated
with quantum criticality. In YFe2Al10, fluctuation of
Fe moments leads to enhanced χ and C/T values yielding large Wilson ratio accompanied
by 27(1/T1T)∼ χ reveal
the dominant role of FM fluctuations in the spin excitation spectra [1].Ta(Fe1−xVx)2
undergoes an itinerant AFM order, but for nominal V doping, the magnetic
properties are reminiscent of itinerant FM at the verge of a FM
instability. The enhanced M(T→0) supported by
C/T∼ -lnT behavior suggest the persistence of FM fluctuations.Additionally,the
51(1/T1T)∼ T−0.8 dependence
in small fields indicates the co-existence of FM and AFM spin fluctuations.The
Korringa product implies FM correlation between
itinerant moments. Presented systems pose special interest since the
bulk and microscopic data support low lying magnetic phase
transitions and both are naturally located in the vicinity
of FM QCP without any external tuning parameter.
[1] Phys. Rev. B (R), in press (2012)