Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 25: Correlated Electrons - Poster Session
TT 25.81: Poster
Mittwoch, 29. März 2006, 14:30–18:30, P1
How many Kondo-ions are seen by the electron spin resonance in Yb1−x Rx Rh2 Si2? — •J. Wykhoff1, J. Sichelschmidt1, S. MaQuilon2, L. Pham2, Z. Fisk2, C. Krellner1, J. Ferstl1, H.-A. Krug von Nidda3, C. Geibel1, and F. Steglich1 — 1Max-Planck-Institut für Chemische Physik fester Stoffe, D-01187 Dresden, Germany — 2Department of Physics, University of California, Davis, CA 95616 USA — 3Experimentalphysik V, Elektronische Korrelationen und Magnetismus, Institut für Physik, Universität Augsburg, 86135 Augsburg, Germany
The heavy-fermion compound Yb Rh2 Si2 is located very close to a magnetic field induced quantum critical point. The unexpected observation of electron spin resonance (ESR) of the Kondo-ion Yb3+ below the Kondo temperature (TK≃25 K) might be a direct verification of the localized moment scenario of quantum criticality [1].
We present the ESR of Yb1−x Rx Rh2 Si2, R = La,Lu. The ESR-line observed below ≈ 30 K vanishes with increasing Lu-concentration. Taking advantage of an improved crystal growth process, we found that the crystal quality and the residual linewidth of the ESR signal are closely related. This suggests that the so-called ESR-bottleneck effect is important for the observability of the ESR-line well below the Kondo temperature. We found that the ESR signal intensity also depends on the Yb-concentration.
[1] J. Sichelschmidt et al., Phys. Rev. Lett. 91, 156401 (2003)