Dielectric Behavior of BaTiO₃/SrTiO₃ Oxide Artificial Lattice by Strain Manipulation

BaTiO₃ (BTO)/SrTiO₃ (STO) artificial lattices have been deposited on (La,Sr)CoO₃/MgO (100) substrate by pulsed laser deposition (PLD). Strain manipulation in the oxide artificial lattice was carried out by varying stacking sequence and period of BTO and STO layers with layer-by-layer growth technique. A wide variation of the lattice distortion for both BTO and STO layers has been obtained from this strain manipulation. The dielectric constant of the BTO and STO lattices was sensitively influenced by the lattice distortion. Moreover, it is found that there exist a certain degree of lattice distortion of the strained BTO and STO lattices leading to a maximum value of their own dielectric constant of the BTO and STO lattices. Consequently, an appropriate combination of stacking period and sequence (resulting in a specific lattice distortion) led to the large dielectric constant (1230) and extremely large tunability (94%) in the BTO/STO oxide artificial lattice.