Dresden 2003 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
MA: Magnetismus
MA 4: Kondo / Schwer-Fermionen / Quasi-Niedrigdimensionale Systeme (gemeinsam mit TT)
MA 4.7: Vortrag
Montag, 24. März 2003, 11:45–12:00, HSZ/405
The Kondo insulator U2Ru2Sn: Magnetic, thermal, and transport properties — •Silke Paschen1, N. Senthilkumaran1, A. Rabis1, M. Baenitz1, 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. — 2School of Physics, Univ. of the Witwatersrand, PO Wits 250, Johannesburg, South Africa — 3Physics Dept., Rand Afrikaans Univ., PO Box 524, Johannesburg, South Africa — 4Dept. of Physics, Graduate School of Science, Nagoya Univ., Nagoya 464-8602, Japan
Heavy-fermion semiconductors or semimetals, usually referred to as ‘Kondo insulators’, are an intriguing set of materials: The origin of the formation of a narrow gap or pseudogap at the Fermi energy is still unclear. The tetragonal compound U2Ru2Sn appears to be a new and the first tetragonal representative of this class of materials. Here we present measurements of magnetic, thermal, and transport properties of single-crystalline samples. The specific heat and the magnetic susceptibility provide evidence for the opening of an energy gap of approximately 150 to 160 K. The magnetic susceptibility is anisotropic, the c axis being the easy magnetic axis. The electrical resistivity varies only slightly with temperature but the Hall coefficient increases strongly in absolute value towards low temperatures. Thus, an increase of mobility must almost compensate the drop of the charge-carrier concentration upon the energy-gap opening. The saturation of the Hall coefficient to an almost sample independent value at the lowest temperatures suggests that the residual density of states within the energy gap might be intrinsic.