Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 20: Correlated Electrons - Poster Session

TT 20.50: Poster

Mittwoch, 28. März 2007, 14:00–17:45, Poster A

Thermal expansion and specific heat of magnetically frustrated (Ni_1−xCo_x)₃V₂O₈ — •Qin Zhang¹, William Knafo^1,2, Kai Grube¹, Hilbert v. Löhneysen^1,2, Christoph Meingast¹, and Thomas Wolf¹ — ¹Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsruhe, Germany — ²Physikalisches Institut, Universität Karlsruhe, D-76128 Karlsruhe, Germany

Ni₃V₂O₈ and Co₃V₂O₈ both have the same basic kagome-staircase structure, leading to geometric frustration of the magnetic ordering of the spins on Ni and Co sites. Both compounds exhibit a number of magnetic phase transitions at low temperatures, which partially relieve the frustration. In addition to magnetic ordering, these compounds also exhibit ferroelectric properties. Here we present thermal expansion and specific heat data on high-quality single crystals of (Ni_1−xCo_x)₃V₂O₈, which allow us to map out the phase diagram of the Ni-Co series, as well as to calculate various pressure derivatives associated with magnetic ordering.