Department of Physics, Columbia University, New York, New York 10027, USA and Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA.
Phys Rev Lett. 2013 Sep 13;111(11):116403. doi: 10.1103/PhysRevLett.111.116403. Epub 2013 Sep 10.
Ab initio calculations are used to predict that a superlattice composed of layers of LaTiO3 and LaNiO3 alternating along the [001] direction is a S=1 Mott insulator with large magnetic moments on the Ni sites, negligible moments on the Ti sites and a charge transfer gap set by the energy difference between Ni d and Ti d states, distinct from conventional Mott insulators. Correlation effects are enhanced on the Ni sites via filling the oxygen p states and reducing the Ni-O-Ni bond angle. Small hole (electron) doping of the superlattice leads to a two-dimensional single-band situation with holes (electrons) residing on the Ni d(x2-y2) (Ti d(xy)) orbital and coupled to antiferromagnetically correlated spins in the NiO2 layer.
从头算预测，由[001]方向交替的 LaTiO3 和 LaNiO3 层组成的超晶格是一个 S=1 的莫特绝缘体，Ni 位具有较大的磁矩，Ti 位的磁矩可以忽略不计，且存在一个由 Ni d 和 Ti d 态之间的能量差决定的电荷转移间隙，这与传统的莫特绝缘体不同。通过填充氧 p 态并减小 Ni-O-Ni 键角，可以增强 Ni 位的关联效应。超晶格的小空穴（电子）掺杂会导致二维单带情况，空穴（电子）占据 Ni d(x2-y2)（Ti d(xy)）轨道，并与 NiO2 层中反铁磁相关的自旋耦合。
