A Novel Room‐Temperature Multiferroic System of Hexagonal Lu1−<italic>x</italic>In<italic>x</italic>FeO3.

Abstract: In the present work, h‐RFeO3 multiferroic ceramics are designed and created by introducing chemical pressure (In‐substitution for Lu) in LuFeO3. Lu1−<italic>x</italic>In<italic>x</italic>FeO3 (<italic>x</italic> = 0‐0.75) ceramics are prepared by the standard solid‐state reaction process. The crystal structure of the present ceramics is tuned from centrosymmetric <italic>Pbnm</italic> (<italic>x</italic> = 0) to non‐centrosymmetric <italic>P63cm</italic> (<italic>x</italic> = 0.4–0.6), and subsequently to centrosymmetric <italic>P63/mmc</italic> (<italic>x</italic> = 0.75), while the <italic>Pbnm</italic> and <italic>P63cm</italic> biphase structure is detected for <italic>x</italic> = 0.25. The Curie temperature for the polar <italic>P63cm</italic> (<italic>x</italic> = 0.4–0.6) phase decreases from >1000 to ≈550 K with increasing <italic>x</italic>. Cloverleaf ferroelectric domain structures are determined in polar Lu0.5In0.5FeO3 samples, and the ferroelectric domain walls at atomic scale are evaluated by the aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy (HAADF STEM), where the spontaneous polarization of 1.73 µC cm−2 is determined for <italic>x</italic> = 0.5. The spontaneous polarization is also confirmed by calculating the site displacement from the centrosymmetric phase based on the X‐ray diffraction (XRD) data. Meanwhile, two magnetic transitions are determined for all compositions, that is, paramagnetic to antiferromagnetic transition at Néel temperature <italic>T</italic>N (≈350 K for <italic>x</italic> = 0.4–0.6), and antiferromagnetic to weak‐ferromagnetic transition at spin‐reorientation temperature <italic>T</italic>SR. The co‐presence of ferroelectric and antiferromagnetic orders confirms the present ceramics as promising room‐temperature multiferroic materials. [ABSTRACT FROM AUTHOR]