Publications by Paolo Radaelli

Spiral-spin-driven ferroelectricity in a multiferroic delafossite AgFeO<inf>2</inf>

Physical Review Letters 109 (2012)

N Terada, DD Khalyavin, P Manuel, Y Tsujimoto, K Knight, PG Radaelli, HS Suzuki, H Kitazawa

We have performed dielectric measurements and neutron diffraction experiments on the delafossite AgFeO 2 . A ferroelectric polarization P 300μC/m2 was observed in a powder sample, below 9AK. The neutron diffraction experiment demonstrated successive magnetostructural phase transitions at T N1 =15K and T N2 =9K. The magnetic structure for 9K≤T≤15K is a spin-density wave with a temperature dependent incommensurate modulation k=(-1,q,12), q 0.384. Below 9AK, the magnetic structure turns into elliptical cycloid with the incommensurate propagation vector k=(-12,q,12), q 0.2026 Based on the deduced magnetic point-group symmetry m1 ′ of the low-temperature polar phase, we conclude that the ferroelectric polarization in AgFeO 2 is perpendicular to the monoclinic b axis and is driven by the inverse Dzyaloshinskii-Moriya effect with two orthogonal components p 1 r ij ×(S i ×S j ) and p 2 S i ×S j . © 2012 American Physical Society.

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