Fig. 3.

Structures from DFT calculations. (A) Possible configurations of La/Sr arrangements. C1 (Sr1–Sr2): two Sr atoms both at the BTO/LSO interface far from each other. C2 (Sr2–Sr1): two Sr atoms are at the interface at nearest neighbor (NN) columnar positions. C3 (Sr3–Sr4): two Sr atoms are in the core at NN columnar position. C4 (Sr1–Sr5): two Sr atoms are at NN rock salt positions at the interface. C5 (Sr3–Sr6): two Sr atoms are at NN rock salt position at the core. C4 configuration is found to have the lowest energy among all other configurations that have been considered for 8/4 SL. In the case of 4/4 SL, C4 configuration has been considered for comparison. Optimized structure of 8/4 SL shows suppression of a⁻a⁻c⁻ distortion and presence of Q^LSMO_Polar mode. (B) Illustration of competing distortions considered in LSMO block [i.e., Q^LSMO_Polar] and antiferrodistortive (a⁻a⁻c⁻) mode and (C) relative stability between competing polar and AFD (a⁻a⁻c⁻) modes [i.e., E (Polar) − E (a⁻a⁻c⁻)].