2D Electron Gas and Jahn-Teller Synergy Enables Al3+ Migration at Oxide Heterointerfaces: Interfacial Engineering for Tunable Oxide Electronics.

Oxide heterointerfaces enable emergent electronic phenomena through interfacial charge reconstruction and lattice coupling. Here, we demonstrate that the synergistic coupling between a 2D electron gas (2DEG) and Mn3+ Jahn-Teller distortion drives Al3+ migration across LaAlO3/NiMn2O4 (LAO/NMO) heterointerfaces. Multiscale characterization (TEM, XAFS, XPS) confirms Al3+ interstitial occupancy and associated local lattice distortion. DFT calculations reveal that the 2DEG reduces Al-vacancy formation energy by ∼50%, while Jahn-Teller distortion provides energetically favorable migration channels, lowering the overall migration barrier to 0.8 eV. Phase-field simulations show that interfacial strain gradients guide Al3+ diffusion and stabilize phase separation. These mechanisms collectively enhance carrier transport (1.6× mobility) and suppress aging (0.28% drift), giving ultrawide-range negative-temperature-coefficient (NTC) behavior (173-1273 K, 99.96% linearity). Our work establishes a mechanistic framework for coupled electrostatic-lattice control of ionic migration, offering design principles for robust functional oxide electronics.