Evidence of Ba-rich surface segregation in Ba 1-x Sr x TiO 3 and Ba-rich surfactant in SrTiO 3 / Ba 1-x Sr x TiO 3 stacks grown by combinatorial pulsed laser deposition - Archive ouverte HAL Accéder directement au contenu
Proceedings/Recueil Des Communications EPJ Web of Conferences Année : 2022

Evidence of Ba-rich surface segregation in Ba 1-x Sr x TiO 3 and Ba-rich surfactant in SrTiO 3 / Ba 1-x Sr x TiO 3 stacks grown by combinatorial pulsed laser deposition

Résumé

The interface of a La 0.7 Sr 0.3 MnO 3 /SrTiO 3 bilayer was modulated by introducing 3 unit cells of Ba 1-x Sr x TiO 3 using Combinatorial Pulsed Laser Deposition. A wide range of chemical compositions was studied within the same sample, with BSTx stoichiometry variable from 0.5 to 1 along Y-axis, while the SrTiO3 overlayer thickness was modified along the X direction [Fig. 1(a)]. We performed high-resolution, laboratory-based angle-resolved XPS studies of the BSTx film surface providing information on the thickness and composition of the surface and sub-surface layers. Based on the attenuation of the La 3d corelevel photoemission signal from the La 0.7 Sr 0.3 MnO 3 bottom layer, the BST layer is 1.2 nm thick. XPS Ba 3d 5/2 core-level spectra were acquired at positions corresponding to different nominal Ba/Sr stoichiometry. In all measurements, the Ba 3d 5/2 core-level spectra can be represented by two main components, i.e. one component at higher binding energy (BE = 780.54 eV) corresponding to surface contribution and the other one at lower binding energy (BE = 778.92 eV) corresponding to sub-surface contribution (Figs. 2 and 3). Going from normal to 60° emission angle and using a 3-unit cell thick film model, the surface to sub-surface intensity ratio clearly evolves providing evidence of a Ba-rich surfactant. The surfactant effect is more significant for lower nominal Ba stoichiometry.

Dates et versions

hal-04011530 , version 1 (02-03-2023)

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Santiago Agudelo-Estrada, Nick Barrett, Christophe Lubin, Jérôme Wolfman, Beatrice Negulescu, et al.. Evidence of Ba-rich surface segregation in Ba 1-x Sr x TiO 3 and Ba-rich surfactant in SrTiO 3 / Ba 1-x Sr x TiO 3 stacks grown by combinatorial pulsed laser deposition. EPJ Web of Conferences, 273, pp.01008, 2022, ⟨10.1051/epjconf/202227301008⟩. ⟨hal-04011530⟩
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