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TT: Fachverband Tiefe Temperaturen
TT 48: Poster Session: Many Body Systems, Quantum Critical Phenomena
TT 48.3: Poster
Mittwoch, 18. März 2020, 15:00–19:00, P2/4OG
Thermodynamic studies of field-induced quantum critical behaviour in the organic spin-dimer system C28H32N4O2 (BY310) — •Christian Thurn1, Paul Eibisch1, Lars Postulka1, Ulrich Tutsch1, Bernd Wolf1, Yulia Borozdina2,3, Martin Baumgarten2, and Michael Lang1 — 1PI, Goethe Uni, Frankfurt/M., SFB/TR49, Deutschland — 2MPI für Polymerforschung, Mainz, SFB/TR49, Deutschland — 3MPI für biologische Kybernetik, Tübingen, Deutschland
Systems of interacting spin dimers provide suitable model systems for studying critical phenomena under well-controlled conditions. Prominent examples include the Bose-Einstein-condensation of triplons in 3D systems [1] or the Berezinskii-Kosterlitz-Thoules scenario in a 2D system [2]. Within this class of materials, spin-dimer systems based on organic radicals stand out due to the high degree of tunability with regard to both the interaction strength as well as the dimensionality. In this work we focus on the tolane-bridged imino-nitroxide radical C28H32N4O2 (BY310) [3]. In BY310 we find quantum-critical points at around 1.8 T and 4.3 T delimiting a B-induced ordered phase for T≤ 0.5 K. We present results of thermal expansion α as well as magnetostriction λ measurements in the field range up to 5.5 T and for temperatures from 1.7 K down to 50 mK. The results are compared with results of the specific heat, the magnetocaloric effect and the ac-susceptibility.
[1] Giamarchi et al., Nat. Phys. 4, No 2, 198-204 (2008)
[2] Tutsch et al., Nat. Commun. 5, 5169 (2014)
[3] Borozdina et al., J. Mater .Chem 5, 9053-9065 (2017)