Park Se Young, Kumar Anil, Rabe Karin M
Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Phys Rev Lett. 2017 Feb 24;118(8):087602. doi: 10.1103/PhysRevLett.118.087602.
The structure and properties of the 1∶1 superlattice of LaVO_{3} and SrVO_{3} are investigated with a first-principles density-functional-theory-plus-U (DFT+U) method. The lowest energy states are antiferromagnetic charge-ordered Mott-insulating phases. In one of these insulating phases, layered charge ordering combines with the layered La/Sr cation ordering to produce a polar structure with a large nonzero spontaneous polarization normal to the interfaces. This polarization, comparable to that of conventional ferroelectrics, is produced by electron transfer between the V^{3+} and V^{4+} layers. The energy of this normal-polarization state relative to the ground state is only 3 meV per vanadium. Under tensile strain, this energy difference can be further reduced, suggesting that the normal-polarization state can be induced by an electric field applied normal to the superlattice layers, yielding an antiferroelectric double-hysteresis loop. If the system does not switch back to the ground state on removal of the field, a ferroelectric-type hysteresis loop could be observed.
采用第一性原理密度泛函理论加U（DFT+U）方法研究了LaVO₃和SrVO₃的1∶1超晶格的结构和性质。最低能量态为反铁磁电荷有序莫特绝缘相。在这些绝缘相之一中，层状电荷有序与层状La/Sr阳离子有序相结合，产生了一种垂直于界面具有大的非零自发极化的极性结构。这种极化与传统铁电体的极化相当，是由V³⁺和V⁴⁺层之间的电子转移产生的。相对于基态，这种法向极化态的能量仅为每个钒原子3毫电子伏特。在拉伸应变下，这种能量差可以进一步减小，这表明法向极化态可以由垂直于超晶格层施加的电场诱导产生，从而产生反铁电双滞回环。如果在去除电场后系统不回到基态，则可以观察到铁电型滞回环。
