Institute of High Pressure Physics

We are pleased to inform about the work on spontaneous and piezoelectric polarization published recently in Materials: P. Strak, P. Kempisty, K. Sakowski, J. Piechota, I. Grzegory, E. Monroy, A. Kaminska, S. Krukowski, Spontaneous and Piezo Polarization Versus Polar Surfaces: Fundamentals and Ab Initio Calculations, Materials 2025, 18(7), 1489; https://doi.org/10.3390/ma18071489

The study discusses the fundamental properties of spontaneous and piezoelectric polarization as well as surface polarization. It has been shown that Landau’s definition of polarization as dipole density can be applied to infinite systems. Two components of polarization were distinguished: bulk polarization and surface polarization. This division is consistent with numerous experimental data. A local model of spontaneous polarization was introduced and used to calculate spontaneous polarization in the form of electric dipole density. This model correctly predicted the values of spontaneous polarization for wurtzite-type nitride semiconductors. At the same time, the model showed zero polarization for the zinc blende lattice. The values of spontaneous polarization obtained for wurtzite group III nitrides were consistent with previous calculations carried out using the Berry phase method. First-principles calculations for wurtzite nitride superlattices using the Heyd–Scuseria–Ernzerhof approximation were performed to calculate polarization fields in regularly strained lattices, showing good agreement with the polarization results. These data were used to determine the piezoelectric parameters of wurtzite nitrides, yielding values consistent with earlier results.