arXiv subjects

Xue-Juan Dong

Publications and source records attributed to Xue-Juan Dong.

4 recordsLinked to original sources

arXiv2021

Electric field induced topological phase transition and large enhancements of spin-orbit coupling and Curie temperature in two-dimensional ferromagnetic semiconductors

Tuning topological and magnetic properties of materials by applying an electric field is widely used in spintronics. In this work, we find a topological phase transition from topologically trivial to nontrivial states at an external electric field of about 0.1 V/A in MnBi$_2$Te$_4$ monolayer that is a topologically trivial ferromagnetic semiconductor. It is shown that when electric field increases from 0 to 0.15 V/A, the magnetic anisotropy energy (MAE) increases from about 0.1 to 6.3 meV, and the Curie temperature Tc increases from 13 to about 61 K. The increased MAE mainly comes from the enhanced spin-orbit coupling due to the applied electric field. The enhanced Tc can be understood from the enhanced $p$-$d$ hybridization and decreased energy difference between $p$ orbitals of Te atoms and $d$ orbitals of Mn atoms. Moreover, we propose two novel Janus materials MnBi$_2$Se$_2$Te$_2$ and MnBi$_2$S$_2$Te$_2$ monolayers with different internal electric polarizations, which can realize quantum anomalous Hall effect (QAHE) with Chern numbers $C$=1 and $C$=2, respectively. Our study not only exposes the electric field induced exotic properties of MnBi2Te4 monolayer, but also proposes novel materials to realize QAHE in ferromagnetic Janus semiconductors with electric polarization.

cond-mat.mtrl-sci↗

arXiv2020

Voting Data-Driven Regression Learning for Discovery of Functional Materials and Applications to Two-Dimensional Ferroelectric Materials

Regression machine learning is widely applied to predict various materials. However, insufficient materials data usually leads to a poor performance. Here, we develop a new voting data-driven method that could generally improve the performance of regression learning model for accurately predicting properties of materials. We apply it to investigate a large family (2135) of two-dimensional hexagonal binary compounds focusing on ferroelectric properties and find that the performance of the model for electric polarization is indeed greatly improved, where 38 stable ferroelectrics with out-of-plane polarization including 31 metals and 7 semiconductors are screened out. By an unsupervised learning, actionable information such as how the number and orbital radius of valence electrons, ionic polarizability, and electronegativity of constituent atoms affect polarization was extracted. Our voting data-driven method not only reduces the size of materials data for constructing a reliable learning model but also enables to make precise predictions for targeted functional materials.

cond-mat.mtrl-sci↗

arXiv2020

Two-dimensional magnetic semiconductors with room Curie temperatures

We propose two-dimensional (2D) Ising-type ferromagnetic semiconductors TcSiTe3, TcGeSe3, and TcGeTe3 with high Curie temperatures around 200-0500 K. Owing to large spin-orbit couplings, the large magnetocrystalline anisotropy energy (MAE), large anomalous Hall conductivity, and large magneto-optical Kerr effect were discovered in these intriguing 2D materials. By comparing all possible 2D MGeTe3 materials (M = 3d, 4d, 5d transition metals), we found a large orbital moment around 0.5 $μ$B per atom and a large MAE for TcGeTe3. The large orbital moments are revealed to be from the comparable crystal fields and electron correlations in these Tc-based 2D materials. The microscopic mechanism of the high Curie temperature is also addressed. Our findings reveal the unique magnetic behaviors of 2D Tc-based materials and present a family of 2D ferromagnetic semiconductors with large MAE and Kerr rotation angles that would have wide applications in designing spintronic devices.

cond-mat.mtrl-sci↗

arXiv2019

Strain-Induced Room-Temperature Ferromagnetic Semiconductors with Large Anomalous Hall Conductivity in Two-Dimensional Cr2Ge2Se6

By density functional theory calculations, we predict a stable two-dimensional (2D) ferromagnetic semiconductor Cr$_2$Ge$_2$Se$_6$, where the Curie temperature $T$$_c$ can be dramatically enhanced beyond room temperature by applying a few percent strain. In addition, the anomalous Hall conductivity in 2D Cr$_2$Ge$_2$Se$_6$ and Cr$_2$Ge$_2$Te$_6$ is predicted to be comparable to that in ferromagnetic metals of Fe and Ni, and is an order of magnitude larger than that in diluted magnetic semiconductor Ga(Mn,As). Based on superexchange interactions, the enhanced $T$$_c$ in 2D Cr$_2$Ge$_2$Se$_6$ by strain can be understood by the decreased energy difference between 3$d$ orbitals of Cr and 4$p$ orbitals of Se. Our finding highlights the microscopic mechanism to obtain the room temperature ferromagnetic semiconductors by strain.

cond-mat.mtrl-sci↗