Dresden 2003 – wissenschaftliches Programm

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MA: Magnetismus

MA 4: Kondo / Schwer-Fermionen / Quasi-Niedrigdimensionale Systeme (gemeinsam mit TT)

MA 4.6: Vortrag

Montag, 24. März 2003, 11:30–11:45, HSZ/405

¹¹⁹ Sn NMR investigations on the semimetal U₂Ru₂Sn — •Michael Baenitz¹, A. Rabis¹, S. Paschen¹, N. Senthilkumaran¹, A.A. Gippius¹, F. Steglich¹, P. de V. duPlessis², A. M. Strydom³, G. Motoyama⁴, and N. K. Sato⁴ — ¹MPI für Chemische Physik fester Stoffe, Nöthnitzer Str.  40, D-01187 Dresden, Germany. — ²Dept. of Physics, Univ. of the Witwatersrand PO Wits 250, Johannesburg, South Africa — ³Dept. of Physics, Rand Afrikaans Univ., PO 524, Johannesburg, South Africa — ⁴Dept. of Physics, Graduate School of Science, Nagoya Univ., Nagoya 464-8602, Japan

¹¹⁹Sn NMR measurements are performed on random and oriented polycrystalline samples and on single crystals of the tetragonal compound U₂Ru₂Sn. Polycrystalline samples of the non-magnetic reference Th₂Ru₂Sn are also investigated. The ¹¹⁹Sn spin - lattice relaxation rate 1/T₁ and the anisotropic Knight shift K are determined. The T dependence of 1/T₁ is very similar to that of CeNiSn with the only difference that the T scale is increased roughly by a factor of 10. Therefore a first estimate gives a (pseudo-) gap value of Δ / k_B≈ 140 K ( ≈ 14 K for CeNiSn). At low temperatures similar to CeNiSn a T₁T=constant behaviour is observed. Susceptibility measurements on oriented polycrystalline powder and single crystals shows a magnetic anisotropy (χ_c(T) > χ_a(T)). K(T) roughly tracks both χ - components. First NMR measurements on oriented powder show that the effect of the magnetic anisotropy on the Knight shift is negligible (K_a−K_c≤ 0.1 %). From this we conclude that the hyperfine coupling A_hf should be larger in the a- than in c- direction.