Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 13: Correlated Electrons: Low-dimensional Systems - Materials 1

TT 13.7: Vortrag

Dienstag, 26. Februar 2008, 11:00–11:15, H 2053

Molecule-based realization of an S=1/2 antiferromagnetic Heisenberg chain — •K. Remović-Langer¹, Y. Tsui¹, U. Tutsch¹, B. Wolf¹, W. Assmus¹, A. Prokofiev⁴, A. Honecker², G. Donath³, and M. Lang¹ — ¹Physikalisches Institut, J.W. Goethe-Universität, Max-von-Laue-Str. 1, SFB/TR 49, D-60438 Frankfurt(M). — ²Institut für Theoretische Physik, Georg-August-Universität Göttingen, D-37077 Göttingen. — ³Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, D-01187 Dresden. — ⁴Institut für Festkörperphysik, Technische Universität Wien, Wiedner Hauptstr. 8-10, A-1040 Wien.

Generally, fine tuning of an external control parameter is required to drive a system to a quantum critical point (QCP). This is different for the spin S=1/2 antiferromagnetic Heisenberg chain (AFHC) which is inherently quantum critical. Here we present magnetic and thermodynamic measurements on single crystals of a copper coordination polymer [Cu(µ-ox)(4-apy)₂(H₂O)]_n. Measurements of the susceptibility, magnetization and specific heat were found to be in full accordance with theoretical predictions for the uniform S=1/2 AFHC with a small magnetic exchange interaction of J/k_B∼ (3.1±0.1)K. The material can be easily tuned to the saturation field B_s∼ 4.2 T, given by gµ_BB_s=2J, which marks the endpoint of a quantum critical line in the T−B plane.