Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 65: Quantum-Critical Phenomena II
TT 65.13: Vortrag
Mittwoch, 14. März 2018, 18:15–18:30, HFT-FT 131
Slow dynamics around the field-induced quantum critical points in the organic spin-dimer system C28H32N4O2 (BY310) — •Paul Eibisch1, Lars Postulka1, Bernd Wolf1, Ulrich Tutsch1, Yulia Borozdina2, Martin Baumgarten2, and Michael Lang1 — 1Physikalisches Institut Geothe-Universität — 2Max Planck Institut für Polymerforschung
Interacting spin-dimer networks exhibit a vast diversity of exotic physical states in connection with a field-induced ordered phase between two quantum critical points. Examples include Bose-Einstein-condensates of magnetic excitations for 3D systems as well as Luttinger liquids in 1D or BKT topological order in 2D. Spin-dimer systems, based on organic radicals, represent suitable candidates to explore this physics due to their high degree of tunability in terms of interaction strengths and dimensionality. We present results of the specific heat, susceptibility and magnetic Grüneisen parameter of the organic spin-dimer system C28H32N4O2, consisting of tolane-bridged iminio nitroxide radicals. Measurements were performed in a field range up to 6 T and for temperatures down to 30 mK. A field-induced ordered phase was found at fields between 1.86 T and 4.3 T for temperatures T≤ 540 mK. Of particular interest is the observation made in AC susceptibility at T< 1 K which indicates very slow dynamics of the spin system in the vicinity of both quantum critical points.