Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 38: Multiferroics

MA 38.5: Vortrag

Donnerstag, 26. März 2009, 16:15–16:30, HSZ 103

Quantum paraelectric-like behavior and giant magnetodielectric coupling in NdFe₃(BO₃)₄ — •Umut Adem¹, Liran Wang¹, Norman Leps¹, Rüdiger Klingeler¹, Christian Hess¹, Alexander Vasiliev², Leonard N. Bezmaternykh³, and Bernd Büchner¹ — ¹Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Germany — ²Moscow State University, Moscow, 119992, Russia — ³Kirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk, 660036, Russia

We have measured the dielectric constant in addition to specific heat, magnetostriction, and magnetization of magnetoelectric NdFe₃(BO₃)₄ single crystals and observed rare quantum paraelectric-like behavior. The dielectric constant increases with decreasing temperature in the temperature range 300 to 5K, more sharply upon the magnetic ordering of Fe spins below 30 K. Application of magnetic field strongly suppresses the additional increase below T_N, resulting at 5K, 8 % change in the dielectric constant under 3 Tesla. We speculate that the dielectric behavior originates from soft phonon mode behavior and the coupling of this soft phonon mode to the magnetic ordering causes the giant magnetodielectric coupling. We compare the quantum paraelectric (incipient ferroelectric) behavior and the magnetodielectric coupling of NdFe₃(BO₃)₄ to that of TbFe₃(BO₃)₄ single crystals.