Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 101: Correlated Electrons: Other Materials

TT 101.9: Vortrag

Donnerstag, 15. März 2018, 17:45–18:00, HFT-FT 101

Magnetic phase diagram and magneto-structural effects in tetra-LiCoPO₄ — •Changhyun Koo¹, Waldemar Hergett¹, Christoph Neef¹, Georg Bothmann², Anton Jesche², Alexander Tsirlin², and Rüdiger Klingeler¹ — ¹Kirchhoff Institute for Physics, Heidelberg University, Heidelberg, Germany. — ²Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg, Germany

The magnetic phase diagram of a new LiCoPO₄ polymorph with tetrahedrally coordinated Co²⁺-ions and Pn2₁a symmetry is built-up based on magnetisation, thermal expansion, specific heat and muon spin rotation data. The system evolves long-range antiferromagnetic order at T_N = 7 K. The magnetic phase diagram shows a variety of competing antiferromagnetic phases. While the Weiss temperature is low, Θ ≈ T_N, our data imply large magnetostriction and anomalous contributions to the specific heat up ∼160 K. The presence of spin fluctuations up to 20T_N is further confirmed by µSR- and previously published NMR data. The nature of the complex magnetic phase diagram and of the spin fluctuation up to high temperatures will be discussed.