Charge Transport and Magnetism in Tm0.03Yb0.97B12

V. Glushkova, A. Azarevich a, M. Anisimov a, A. Bogach a, S. Demishev a, A. Dukhnenko b, V. Filipov b, K. Flachbart c, S. Gabáni c, S. Gavrilkin d, M. Kondrin e, N. Shitsevalova b and N. Sluchanko a aProkhorov General Physics Institute of RAS, Vavilov Str. 38, 119991 Moscow, Russia bFrantsevich Institute for Problems of Materials Science, NAS, Krzhyzhanovsky Str. 3, 03680 Kiev, Ukraine cInstitute of Experimental Physics, SAS, Watsonova 47, 040 01 Košice, Slovakia dLebedev Physical Institute of RAS, Leninskii pr. 53, 119991 Moscow, Russia eVereshchagin Institute of High Pressure Physics of RAS, Troitsk, 142190 Moscow, Russia

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Transport and magnetic properties of polycrystalline Tm0.03Yb0.97B12 samples were investigated at temperatures 1.8-300 K in magnetic fields up to 9 T. The activated behavior of resistivity, the Hall coefficient and thermopower is described in terms of a narrow gap εg ≈16.6 meV, which controls the charge transport in Tm0.03Yb0.97B12 at T>40 K. The maximum of magnetic susceptibility found at 50 K is shown to be induced by a spin gap Δ ≈4.7 meV being close to the half of the spin fluctuation energy in YbB12. Large diffusive thermopower S=AT, A=-29.1 μV/K2 and the Pauli susceptibility χ0 ≈ 7.2×10-3 emu/mol found below 20 K seem to be associated with the many-body resonance, which corresponds to states with an enhanced effective mass m* ≈ 250m0 (m0 - free electron mass). The effective parameters of magnetic centers and the analysis of anomalies favor the nonequivalent states of substitute Tm ions.

DOI: 10.12693/APhysPolA.131.985 PACS numbers: 72.15.Gd, 72.15.Jf, 71.27.+a