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TT: Tiefe Temperaturen
TT 6: Postersitzung I (Amorphe- u. Tunnelsysteme, Niedrigdimensionale Systeme, Supraleitung: Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter)
TT 6.18: Poster
Montag, 24. März 2003, 14:30–19:00, P2c, P2d
Thermal transport properties of the one-dimensional S = 1/2 antiferromagnet Yb4(As1−xPx)3 (x = 0 and 0.3 ) — •Adriana Sanchez, Silke Paschen, Bodo Wand, and Frank Steglich — MPI für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, D - 01187 Dresden
The semimetallic quasi-one-dimensional S = 1/2 Heisenberg antiferromagnet Yb4(As1−xPx)3 (x = 0 and 0.3 ) was studied by thermal conductivity κ measurements at low temperatures. κ was measured in the temperature range between 0.1 and 7 K and in applied magnetic fields up to 8 T. For both samples, κ (T) was found to follow the relation aT+bT2 between 0.4 and 6 K at zero magnetic field. We attribute this dependence to the dominating role of magnons: The magnons act as heat carriers at the lowest temperatures (aT term) and as scatterers for the phonons at higher temperatures (bT2 term). Below 0.4 K, the thermal conductivity drops below the aT+bT2 law, in agreement with the deviation from the magnon-related γT term in the specific heat due to spin-glass freezing. For both samples, above 1K, κ (B) decreases with increasing magnetic field, the opening of a gap in the magnon-excitation spectrum being a possible explanation of this behavior.