Room temperature polar structure and multiferroicity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>BaFe</mml:mi><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub><mml:mi>Se</mml:mi><mml:msub><mml:mrow/><mml:mn>3</mml:mn></mml:msub></mml:math>
Wen-Gen Zheng, V. Balédent, Marie-Bernadette Lepetit, Pascal Retailleau, Elsa Van Elslande, C. Pasquier, Pascale Auban‐Senzier, A. Forget, D. Colson, P. Foury-Leylekian
Abstract
The understanding of the superconducting phase under pressure in the famous iron-based spin ladder ${\mathrm{BaFe}}_{2}{\mathrm{Se}}_{3}$ commands a perfect understanding of the structural properties. We present an accurate single crystal x-ray analysis which demonstrates that the structure admitted until now at room temperature is totally ruled out. We show that the system has a polar structure already at 300 K and is thus ferroelectric. Its structure is modified below the N\'eel transition and the polarization is intensified. These features unambiguously prove the multiferroic character of ${\mathrm{BaFe}}_{2}{\mathrm{Se}}_{3}$ as proposed theoretically. This system evidences a competition between multiferroicity and superconductivity.