Unusual magnetoelectric effect in paramagnetic rare-earth langasite

Abstract

Violation of time reversal and spatial inversion symmetries has profound consequences for elementary particles and cosmology. Spontaneous breaking of these symmetries at phase transitions gives rise to unconventional physical phenomena in condensed matter systems, such as ferroelectricity induced by magnetic spirals, electromagnons, non-reciprocal propagation of light and spin waves, and the linear magnetoelectric (ME) effect - the electric polarization proportional to the applied magnetic field and the magnetization induced by the electric field. Here, we report the experimental study of the holmium-doped langasite, Ho${}_x$La${}_{3-x}$Ga${}_5$SiO${}_{14}$, showing a puzzling combination of linear and highly non-linear ME responses in the disordered paramagnetic state: its electric polarization grows linearly with the magnetic field but oscillates many times upon rotation of the magnetic field vector. We propose a simple phenomenological Hamiltonian describing this unusual behavior and derive it microscopically using the coupling of magnetic multipoles of the rare-earth ions to the electric field.

arXiv comment8 pages, 3 figures

References in corpus (5)

• Possible evidence for electromagnons in multiferroic manganites
• Giant Magnetoelectric Effect in HoAl_3(BO_3)_4
• Magnetic and dielectric properties in the langasite-type compounds : A3BFe3D2O14 with A=Ba, Sr, Ca, B=Ta, Nb, Sb and D=Ge, Si
• Parity Broken Chiral Spin Dynamics in Ba${}_3$NbFe${}_3$Si${}_2$O${}_{14}$
• Magnetoelectric memory function with optical readout

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• Magnetic anisotropy and exchange paths for octa- and tetrahedrally coordinated Mn${}^{2+}$ ions in the honeycomb multiferroic Mn${}_2$Mo${}_3$O${}_8$
• The effect of local distortions on magnetic and magnetoelectric properties of paramagnetic Pr3Ga5SiO14 langasite
• Quadratic magnetoelectric effect during field cooling in sputter grown Cr${}_2$O${}_3$ films
• Resolving the local distortions of Ising-like moments in magnetoelectric Ho-doped langasite
• Magnetic and thermodynamic studies on the distorted kagome magnet Pr${}_3$BWO${}_9$