2D Electron Gas and Jahn–Teller Synergy Enables Al 3+ 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 Mn 3+ Jahn–Teller distortion drives Al 3+ migration across LaAlO 3 /NiMn 2 O 4 (LAO/NMO) heterointerfaces. Multiscale characterization (TEM, XAFS, XPS) confirms Al 3+ 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 Al 3+ 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.