Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 33: Superconductivity, Measuring Devices, Matter at Low Temperature: Poster Session
TT 33.74: Poster
Mittwoch, 28. März 2012, 15:00–19:00, Poster B
High-magnetic-field investigation of CoCr2O4 — •A. V. Pronin1, M. Uhlarz1, R. Beyer1, T. Fischer1, J. Wosnitza1, B. P. Gorshunov2,3,4, G. A. Komandin2, A. S. Prokhorov2,3, M. Dressel4, A. A. Bush5, and V. I. Torgashev6 — 1Hochfeld-Magnetlabor Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Germany — 2A. M. Prokhorov Institute of General Physics, Russian Academy of Sciences, Moscow, Russia — 3Moscow Institute of Physics and Technology (State University), Russia — 41. Physikalisches Institut, Universität Stuttgart, Germany — 5Moscow Institute of Radiotechnics, Electronics, and Automation, Russia — 6Faculty of Physics, Southern Federal University, Rostov-on-Don, Russia
We report on magnetic, optical, and thermodynamic properties of multiferroic CoCr2O4 in magnetic fields up to 14 T. We have found indications of a new phase transition at T∗ = 5 − 6 K. The phase between T∗ and the lock-in transition at 15 K is characterized by magnetic irreversibility. At higher fields the irreversibility increases. Heat-capacity measurements confirm the transition at T∗, and also show the irreversible behaviour. We construct a field-temperature phase diagram of CoCr2O4. Below the ferrimagnetic transition (94 K), the low-frequency (terahertz) optical response is dominated by a magnetic exchange mode, which shows an anomalous temperature dependence and a softening at the structural transition (26 K).
Part of this work has been supported by EuroMagNET under the EU contract no. 228043.