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TT: Tiefe Temperaturen
TT 6: Postersitzung I: Josephsonkontakte und SQUIDs, Supraleitung: Theorie, Korrelierte Elektronen, Niederdimensionale Systeme, Magnetotransport, Quantenhalleffekt, Kohlenstoff-Nanoröhrchen, Quantenflüssigkeiten
TT 6.56: Poster
Monday, March 26, 2001, 14:30–17:00, Rang S\ 3
Magnetic anisotropy of the low-T specific heat and ac-susceptibility of one-dimensional S=1/2 Heisenberg antiferromagnet Yb4As3 — •H. Aoki1, T. Cichorek1, P. Gegenwart1, F. Steglich1, and A. Ochiai2 — 1MPI for Chemical Physics of Solids, Dresden, Germany — 2Tohoku University, Sendai, Japan
One of the unique properties of the rare-earth compound Yb4As3 is the charge-ordering transition at Tco=293 K which leads to the formation of one-dimentional Yb3+ (S=1/2) chains. Below Tco the smaller Yb3+ ions order along one of the possible four space diagonals which usually results in the formation of a multi-domain structure. The low-T specific heat and susceptibility of Yb4As3 are well described by quantum sine-Gordon soliton model of a one-dimensional S=1/2 Heisenberg antiferromagnet. The existence of the antiferromagnetic S=1/2 Heisenberg chains at low temperature was clearly confirmed via inelastic neutron-scattering experiments. Recently, our detailed investigation of the specific heat and ac-susceptibility shows another weak magnetic interaction, which occurs around 150 mK due to interchain-coupling effects. Its behavior seems to be very similar to that expected for spin glasses.
In order to check the validity of the theoretical model we studied the anisotropy of the low-T properties of Yb4As3 on single-domain samples in magnetic fields up to 10 T. Note that solitons exist only for fields perpendicular to the spin chains. A preferential orientation of the domains was induced by the application of uniaxial stress prior to cooling through Tco. Thereby, we could also investigate the influence of different domain configurations on the spin-glass like anomaly in Yb4As3.