Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 26: CE: Heavy Fermions

TT 26.9: Vortrag

Mittwoch, 24. März 2010, 16:15–16:30, H21

Electron Spin Resonance of YbRh₂Si₂ under pressure — •J. Sichelschmidt¹, H.-A. Krug von Nidda², D. Zakharov², I. Fazlishanov³, J. Wykhoff¹, T. Gruner¹, C. Krellner¹, C. Klingner¹, C. Geibel¹, F. Steglich¹, and A. Loidl² — ¹MPI Chem. Physik fester Stoffe, 01187 Dresden — ²EP V, EKM, Univ. Augsburg, 86135 Augsburg — ³E. K. Zavoisky Phys. Techn. Inst., 420029 Kasan, Russia

We investigated the electron spin resonance (ESR) in the heavy-fermion metal YbRh₂Si₂ by applying hydrostatic pressure up to 3 GPa. We found that pressure increases the temperature dependence of the g factor and broadens the ESR line. These effects are similar to those observed in Yb(Rh_1−xCo_x)₂Si₂ where Co substitution for Rh induces chemical pressure. However, the effect of chemical and external pressure on the ESR is not identical indicating the relevance of Co induced disorder on the spin dynamics. We compare our pressure ESR results with the behavior of the Gd ESR in CeAl₃ [1]. This reveals a similar behavior pointing on one hand to a local character Yb³⁺-ESR, on the other hand on the properties of a heavy quasiparticle spin resonance upon changing the hybridization strength between 4f and conduction electrons [2]. Both findings are consistent with the properties of a collective 4f-conduction electron spin mode which is supported by the Kondo effect [3].

[1] B. Elschner, A. Loidl, Handb.Phys.Chem.Rare Earths 24, 221(1997)

[2] P. Wölfle, E. Abrahams, arXiv 0909 3552v1 (2009)

[3] B.I. Kochelaev et al., Eur. Phys. J. B 72 (2009)