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arXiv · 1807.10457

Magnetic Structural Unit with Convex Geometry: a Building Block Hosting an Exchange-striction-driven Magnetoelectric Coupling

Kenta Kimura·Yasuyuki Kato·Kunihiko Yamauchi·Atsushi Miyake·Masashi Tokunaga·Akira Matsuo·Koichi Kindo·Mitsuru Akaki·Masayuki Hagiwara·Shojiro Kimura·Masayuki Toyoda·Yukitoshi Motome·Tsuyoshi Kimura
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Abstract

We perform a combined experimental and theoretical study of a magnetic-field ($B$) induced evolution of magnetic and ferroelectric properties in an antiferromagnetic material Pb(TiO)Cu$_4$(PO$_4$)$_4$, whose structure is characterized by a staggered array of Cu$_4$O$_{12}$ magnetic units with convex geometry known as square cupola. Our experiments show a $B$-induced phase transition from a previously reported low-$B$ linear magnetoelectric phase to a new high-$B$ magnetoelectric phase, which accompanies a 90$^\circ$ flop of electric polarization and gigantic magnetodielectric effect. Moreover, we observe a $B$-induced sign reversal of ferroelectric polarization in the high-$B$ phase. Our model and first-principles calculations reveal that the observed complex magnetoelectric behavior is well explained in terms of a $B$-dependent electric polarization generated in each Cu$_4$O$_{12}$ unit by the so-called exchange striction mechanism. The present study demonstrates that the materials design based on the magnetic structural unit with convex geometry deserves to be explored for developing strong magnetoelectric couplings.

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Kenta Kimura, Yasuyuki Kato, Kunihiko Yamauchi, Atsushi Miyake, Masashi Tokunaga, Akira Matsuo, Koichi Kindo, Mitsuru Akaki, Masayuki Hagiwara, Shojiro Kimura, Masayuki Toyoda, Yukitoshi Motome, Tsuyoshi Kimura. 2018-07-27. Magnetic Structural Unit with Convex Geometry: a Building Block Hosting an Exchange-striction-driven Magnetoelectric Coupling. https://doi.org/10.1103/physrevmaterials.2.104415

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