The origin of two-dimensional electron gas formed in LaGaO 3 /SrTiO 3

Self Cite

First-principles calculations are performed to explore the possibility of generating the two-dimensional electron gas (2DEG) at the interface between LaGaO 3 /KTaO 3 and NdGaO 3 /KTaO 3 (001) heterostructures. Two different modelsi.e., the superlattice model and the thin film model -are used to conduct a comprehensive investigation of the origin of charge carriers. For the symmetric superlattice model, the LaGaO 3 (or NdGaO 3 ) film is nonpolar. The 2DEG with carrier density on the order of 10 14 cm −2 originates from the Ta d xy electrons contributed by both LaGaO 3 (or NdGaO 3 ) and KTaO 3 . For the thin film model, large polar distortions occur in the LaGaO 3 and NdGaO 3 layer, which entirely screens the built-in electric field and prevents electrons from transferring to the interface. Electrons of KTaO 3 are accumulated at the interface, contributing to the formation of the 2DEG. All the heterostructures exhibit conducting properties regardless of the film thickness. Compared with the Ti d xy electrons in SrTiO 3 -based heterostructures, the Ta d xy electrons have small effective mass and they are expected to move with higher mobility along the interface. These findings reveal the promising applications of 2DEG in novel nanoelectronic devices.

Section: Superlattice Modelsupporting

confidence: 65%

Section: Superlattice Modelmentioning

confidence: 99%

Prediction of high-mobility two-dimensional electron gas at KTaO ₃ -based heterointerfaces

Wang

et al. 2019

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“…However, the average displacements between anions and cations near the interface in the case of −P are larger than that of in the case of +P, owing that the direction of the built-in electric field due to ferroelectric distortion in the LTO part is the same as the direction of the polarized electric field of the BFO. [52] This qualitatively shows that the amount of charge transfer in the case of −P is greater than that of in the case of +P. The transferred electrons caused by this kind of ferroelectric distortion ultimately lead to the emergence of 2DEG in the HSs.…”

Section: Resultsmentioning

confidence: 87%

Magnetoelectric coupling effect of polarization regulation in BiFeO₃/LaTiO₃ heterostructures*

Jin¹,

Ren²,

Sun³

et al. 2021

An effective regulation of the magnetism and interface of ferromagnetic materials is not only of great scientific significance, but also has an urgent need in modern industry. In this work, by using the first-principles calculations, we demonstrate an effective approach to achieve non-volatile electrical control of ferromagnets, which proves this idea in multiferroic heterostructures of ferromagnetic LaTiO3 and ferroelectric BiFeO3. The results show that the magnetic properties and two-dimensional electron gas concentrations of LaTiO3 films can be controlled by changing the polarization directions of BiFeO3. The destroyed symmetry being introduced by ferroelectric polarization of the system leads to the transfer and reconstruction of the Ti-3d electrons, which is the fundamental reason for the changing of magnetic properties. This multiferroic heterostructures will pave the way for non-volatile electrical control of ferromagnets and have potential applications.

“…Figure 5(a) shows that the bands of the Ti 3d electrons states are near to the Fermi level, and the Ti t 2g electrons states split into the d xy and d xz /d yz states, the in-plane d xy orbital becomes the lowest conduction bands with low effective mass, so the contribution of the 2DEG comes from the partly filled d xy orbitals of Ti atom of the interface. In our previous calculations, [26]…”

Section: -2mentioning

confidence: 88%

“…[16][17][18][19][20] Especially, the heterostructures of LaGaO 3 (LGO) and STO have received more and more attention due to their two-dimensional electrical properties at interface. [21][22][23][24][25][26] In 2010, Perna et al [21] first observed the 2DEG formed at the interface of LGO/STO, which exhibits some properties similar to those of LAO/STO, such as superconducting at low temperature (T c = 150 mK for both heterostructures). The onset of conductivity takes place at 4 unit cells (u.c.)…”

Section: Introductionmentioning

confidence: 99%

Electrical property effect of oxygen vacancies in the heterojunction of LaGaO ₃ / SrTiO ₃

Wang¹,

Li²,

Zhang³

et al. 2017

Self Cite

Density functional theory within the local density approximation is used to investigate the effect of the oxygen vacancy on the LaGaO 3 /SrTiO 3 (001) heterojunction. It is found that the energy favorable configuration is the oxygen vacancy located at the 3 rd layer of the STO substrate, and the antiferrodistortive distortion is induced by the oxygen vacancy introduced on the SrTiO 3 side. Compared with the heterojunction without introducing oxygen vacancy, the heterojunction with introducing the oxygen vacancy does not change the origin of the two-dimensional electron gas (2DEG), that is, the 2DEG still originates from the d xy electrons, which are split from the t 2g states of Ti atom at interface; however the oxygen vacancy is not beneficial to the confinement of the 2DEG. The extra electrons caused by the oxygen vacancy dominantly occupy the 3d x 2 −y 2 orbitals of the Ti atom nearest to the oxygen vacancy, thus the density of carrier is enhanced by one order of magnitude due to the introduction of oxygen vacancy compared with the density of the ideal structure heterojunction.