Eur. Phys. J. B 71, 393-399 (2009)
https://doi.org/10.1140/epjb/e2009-00209-1

Magnetodielectric coupling by exchange striction in Y₂Cu₂O₅

¹ Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
² CEA-Grenoble INAC/SPSMS/MDN, 17 rue des martyrs, 38054 Grenoble Cedex 9, France
³ Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France

Corresponding author: ^a t.t.m.palstra@rug.nl

Received: 27 February 2009
Published online: 19 June 2009

Abstract

We have studied the magnetodielectric response of Y₂Cu₂O₅, the so-called blue phase in the Y₂O₃-CuO-BaO phase diagram. Based on symmetry principles, we predict and demonstrate magneto-dielectric coupling on a single crystal sample. We report an anomaly in the dielectric constant at the ordering temperature of the Cu spins. We probe the magnetic field-induced phase transitions between four different magnetic phases using magneto-capacitance measurements, demonstrating relatively strong magnetodielectric coupling. We observe an increase in dielectric constant in the spin-flip phase where there exists spontaneous magnetization. We construct a detailed magnetic phase diagram. The magnetodielectric coupling is analyzed in terms of striction induced by symmetric superexchange and optical phonon frequency shifts.