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1. Identifying alternative ferroelectric materials beyond Hf(Zr)O ₂

   https://doi.org/10.1063/5.0028611  

   Guo, Jing; Clima, Sergiu; Pourtois, Geoffrey; Van Houdt, Jan (December 2020, Applied Physics Letters)

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2. Giant Superelastic Piezoelectricity in Flexible Ferroelectric BaTiO ₃ Membranes

   https://doi.org/10.1021/acsnano.0c01615  

   Elangovan, Hemaprabha; Barzilay, Maya; Seremi, Sahar; Cohen, Noy; Jiang, Yizhe; Martin, Lane W.; Ivry, Yachin (April 2020, ACS Nano)

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3. Epitaxial AlBN/β‐Nb ₂ N Ferroelectric/Superconductor Heterostructures

   https://doi.org/10.1002/pssr.202400157  

   Savant, Chandrashekhar; Nguyen, Thai‐Son; Vishwakarma, Saurabh; Lee, Joongwon; Ithepalli, Anand; Chen, Yu‐Hsin; Nomoto, Kazuki; Rana, Farhan; Smith, David J; Xing, Huili Grace; et al (November 2024, physica status solidi (RRL) – Rapid Research Letters)

   We report the growth of AlBN/β‐Nb₂N nitride epitaxial heterostructures in which the AlBN is ferroelectric, and β‐Nb₂N with metallic resistivity ≈40 μ at 300 K becomes superconducting belowT_C ≈ 0.5 K. Using nitrogen plasma molecular beam epitaxy, we grow hexagonal β‐Nb₂N films on c‐plane Al₂O₃substrates, followed by wurtzite AlBN. The AlBN is in epitaxial registry and rotationally aligned with the β‐Nb₂N, and the hexagonal lattices of both nitride layers make angles of 30° with the hexagonal lattice of the Al₂O₃substrate. The B composition of the AlBN layer is varied from 0 to 14.7%. It is found to depend weakly on the B flux, but increases strongly with decreasing growth temperature, indicating a reaction rate‐controlled growth. The increase in B content causes a non‐monotonic change in the a‐lattice constant and a monotonic decrease in the c‐lattice constant of AlBN. Sharp, abrupt epitaxial AlBN/β‐Nb₂N/Al₂O₃heterojunction interfaces and close symmetry matching are observed by transmission electron microscopy. The observation of ferroelectricity and superconductivity in epitaxial nitride heterostructures opens avenues for novel electronic and quantum devices. 

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4. Domain alignment within ferroelectric/dielectric PbTiO ₃ /SrTiO ₃ superlattice nanostructures

   https://doi.org/10.1039/c7nr07203a  

   Park, Joonkyu; Mangeri, John; Zhang, Qingteng; Yusuf, M. Humed; Pateras, Anastasios; Dawber, Matthew; Holt, Martin V.; Heinonen, Olle G.; Nakhmanson, Serge; Evans, Paul G. (January 2018, Nanoscale)

   The ferroelectric domain pattern within lithographically defined PbTiO 3 /SrTiO 3 ferroelectric/dielectric heteroepitaxial superlattice nanostructures is strongly influenced by the edges of the structures. Synchrotron X-ray nanobeam diffraction reveals that the spontaneously formed 180° ferroelectric stripe domains exhibited by such superlattices adopt a configuration in rectangular nanostructures in which domain walls are aligned with long patterned edges. The angular distribution of X-ray diffuse scattering intensity from nanodomains indicates that domains are aligned within an angular range of approximately 20° with respect to the edges. Computational studies based on a time-dependent Landau–Ginzburg–Devonshire model show that the preferred direction of the alignment results from lowering of the bulk and electrostrictive contributions to the free energy of the system due to the release of the lateral mechanical constraint. This unexpected alignment appears to be intrinsic and not a result of distortions or defects caused by the patterning process. Our work demonstrates how nanostructuring and patterning of heteroepitaxial superlattices allow for pathways to create and control ferroelectric structures that may appear counterintuitive. 

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5. Bend-Induced Ferroelectric Domain Walls in α-In ₂ Se ₃

   https://doi.org/10.1021/acsnano.3c01311  

   Han, Edmund; Nahid, Shahriar Muhammad; Rakib, Tawfiqur; Nolan, Gillian; Ferrari, Paolo F.; Hossain, M. Abir; Schleife, André; Nam, SungWoo; Ertekin, Elif; van der Zande, Arend M.; et al (April 2023, ACS Nano)