- Chen, Zuhuang
- Chen, Zhanghui
- Liu, ZQ
- Holtz, ME
- Li, CJ
- Wang, X Renshaw
- Lü, WM
- Motapothula, M
- Fan, LS
- Turcaud, JA
- Dedon, LR
- Frederick, C
- Xu, RJ
- Gao, R
- N'Diaye, AT
- Arenholz, E
- Mundy, JA
- Venkatesan, T
- Muller, DA
- Wang, L-W
- Liu, Jian
- Martin, LW
- et al.
Emergent phenomena at polar-nonpolar oxide interfaces have been studied intensely in pursuit of next-generation oxide electronics and spintronics. Here we report the disentanglement of critical thicknesses for electron reconstruction and the emergence of ferromagnetism in polar-mismatched LaMnO_{3}/SrTiO_{3} (001) heterostructures. Using a combination of element-specific x-ray absorption spectroscopy and dichroism, and first-principles calculations, interfacial electron accumulation, and ferromagnetism have been observed within the polar, antiferromagnetic insulator LaMnO_{3}. Our results show that the critical thickness for the onset of electron accumulation is as thin as 2 unit cells (UC), significantly thinner than the observed critical thickness for ferromagnetism of 5 UC. The absence of ferromagnetism below 5 UC is likely induced by electron overaccumulation. In turn, by controlling the doping of the LaMnO_{3}, we are able to neutralize the excessive electrons from the polar mismatch in ultrathin LaMnO_{3} films and thus enable ferromagnetism in films as thin as 3 UC, extending the limits of our ability to synthesize and tailor emergent phenomena at interfaces and demonstrating manipulation of the electronic and magnetic structures of materials at the shortest length scales.