Физика Низких Температур: Том 46, Выпуск 12 (Декабрь 2020), c. 1377-1385 ( к оглавлению , назад )
Intrinsic nanostructures on the (001) surface of strontium titanate at low temperatures
V. O. Hamalii1, A. V. Peschanskii1, А. І. Popov2, and N. V. Krainyukova1
1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine Kharkiv 61103, Ukraine
2Institute of Solid State Physics, University of Latvia, Riga LV-1063, Latvia
Received August 19, 2020, published online October 21, 2020
Atomically smooth (001) surfaces of SrTiO3 cut from the high-quality single crystals at two different miscut angles 0.9 and 7.0 deg between the real flat surfaces and crystallographic planes (001) were analyzed by means of the reflection high energy electron diffraction (RHEED) method from the room down to liquid helium temperatures. The diffraction patterns typical of the RHEED geometry close to ideal for a small miscut angle and those exhibiting distinct features of the specific periodicity associated with regular steps, which form due to the larger miscut angle, are presented. The surface symmetry and energetics were shown to impose differences in lattice parameters in parallel to a surface with respect to the bulk. This effect results in weak incommensurability between lattice parameters in surface layers and the bulk values relaxed due to step edges and misfit dislocations. The special surface nanostructures formed on the etched surfaces treated in chemically active solvents are also analyzed. The intrinsic nanostructures on single crystal surfaces open new prospects for applications when the ordered and controlled nanoscale architecture is required.
Key words: strontium titanate, surface nanostructures, surface incommensurability, reflection high-energy electron diffraction, Raman spectroscopy.