Multiferroicity in geometrically frustrated α - M Cr 2 O 4 systems ( M = Ca, Sr, Ba)

Li. Zhao; Tian-Wey Lan; Kuen-Jen Wang; Chia-Hua Chien; Tsu-Lien Hung; Jiu-Yong Luo; Wei-Hsiang Chao; Chung-Chieh Chang; Yang-Yuan Chen; Maw-Kuen Wu; Christine Martin

Multiferroicity in geometrically frustrated α - M Cr 2 O 4 systems ( M = Ca, Sr, Ba)

Li. Zhao ¹ Tian-Wey Lan ¹ Kuen-Jen Wang ¹ Chia-Hua Chien ¹ Tsu-Lien Hung ¹ Jiu-Yong Luo ¹ Wei-Hsiang Chao ¹ Chung-Chieh Chang ¹ Yang-Yuan Chen ¹ Maw-Kuen Wu ¹ Christine Martin ²

1 Institute of Physics, Academia Sinica

2 CRISMAT - Laboratoire de cristallographie et sciences des matériaux

Abstract : We have successfully synthesized three quasi-two-dimensional geometrically frustrated magnetic compounds (α-MCr2O4, M= Ca, Sr, Ba) using the spark-plasma-sintering technique. All these members of the α-MCr2O4 family consist of the stacking planar triangular lattices of Cr3+ spins (S=3/2), separated by nonmagnetic alkaline-earth ions. Their corresponding magnetic susceptibility, specific heat, dielectric permittivity, and ferroelectric polarization are systematically investigated. A long-range magnetic ordering arises below the Néel temperature (around 40 K) in each member of the α-MCr2O4 family, which changes to the quasi-120∘ proper-screw-type helical spin structure at low temperature. A very small but confirmed spontaneous electric polarization emerges concomitantly with this magnetic ordering. The direction of electric polarization is found within the basal triangular plane. The multiferroicity in α-MCr2O4 can not be explained within the frameworks of the magnetic exchange striction or the inverse Dzyaloshinskii-Moriya interaction. The observed results are more compatible with the newly proposed Arima mechanism that is associated with the d-p hybridization between the ligand and transition-metal ions, modified by the spin-orbit coupling. The evolution of multiferroic properties with the increasing interplanar spacing (as M changes from Ca to Ba) reveals the importance of interlayer interaction in this new family of frustrated magnetic systems.

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Chimie / Matériaux

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https://hal-normandie-univ.archives-ouvertes.fr/hal-02264054
Contributeur : Elisabeth van T Hof <>
Soumis le : mardi 6 août 2019 - 11:07:59
Dernière modification le : mercredi 25 septembre 2019 - 16:36:55

Multiferroicity in geometrically frustrated α - M Cr 2 O 4 systems ( M = Ca, Sr, Ba)

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Multiferroicity in geometrically frustrated α - M Cr 2 O 4 systems ( M = Ca, Sr, Ba)

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