First-principles studies of a two-dimensional electron gas at the interface of polar/polar LaAlO₃/KNbO₃ superlattices

Abstract

We explored the possibility of producing a two-dimensional electron gas (2DEG) in polar/polar (LaAlO3)m/(KNbO3)n perovskite superlattices that have N type and P type interfaces using the first-principles electronic structure calculations.

Predicting the structural, electronic and magnetic properties of few atomic-layer polar perovskite

“…This could be explained by the "polar catastrophe" of perovskite materials when an electrostatic instability happens as layer thickness is accumulated to certain threshold. Further, there are many compensation mechanisms to stabilize such as electrostatic shielding by 2DEG, charge transfer, surface reconstruction, chemical doping and adsorption [15][16][17]19,29]. As displayed in Fig.…”

“…Bulk KTaO3 perovskite is an incipient ferroelectric material [12] with a relatively large band gap 3.64 eV [13], which has been studied for over sixty years [14]. A number of novel properties have been discovered in this system by using methods like doping, size effect, dimension or interface engineering [15,16]. For example, people found the 2D electron gas (2DEG) with strong spin-orbit coupling on its polar surface [17,18], and the superconductivity by electrostatic carrier doping [19].…”

Tunable Magnetism and Insulator–Metal Transition in Bilayer Perovskites

“…Bulk KNbO 3 (KNO) and KTaO 3 (KTO) perovskites have been studied for over 70 years. , The former is famous as a room temperature lead-free ferroelectric material, while the latter is so-called incipient ferroelectric . Some exotic properties based on them have been realized by doping, size, dimension, or interface engineering, including the magnetic response in nanocrystalline KNO, two-dimensional electron gas (2DEG) in their various heterostructures, , 2DEG in the KTO polar surface with strong spin–orbit coupling, , and the superconductivity in KTO by electrostatic carrier doping . It is thus expected that their electronic and magnetic properties will be strongly modulated when the perovskites are approaching the 2D limit.…”

“…(2DEG) in their various heterostructures [20,21], 2DEG in KTO polar surface with strong spin-orbit coupling [22,23], and the superconductivity in KTO by electrostatic carrier doping [24]. It is thus expected that their electronic and magnetic properties will be strongly modulated when the perovskites are approaching the 2D limit.…”

Piezoelectric properties of ferroelectric perovskite superlattices with polar discontinuity

“…Until now, theoretical studies of superlattices with the polar discontinuity have focused on studying the distribution of polarization and electric field in these structures and on finding the conditions for the appearance of a two-dimensional electron gas at the interface [59][60][61][62][63][64][65][66][67][68][69][70]. The questions of the stability of the high-symmetry polar structure in such SLs, possible phase transitions in them, and the physical properties of low-symmetry phases were not analyzed.…”