Correlated electrons in the flat band in the charge density wave state of 4Hb−TaSexS2−x

Correlated electrons in the flat band in the charge density wave state of 4Hb−TaSexS2−x

Yanyan Geng#, Jianfeng Guo#, Fanyu Meng#, Manyu Wang, Shuo Mi, Li Huang, Rui Xu, Fei Pang, Kai Liu, Shancai Wang, Hong-Jun Gao, Weichang Zhou, Wei Ji*, Hechang Lei*, and Zhihai Cheng*

Many intriguing quantum states of matter, such as unconventional superconductivity, magnetic phases, and fractional quantum Hall physics, emerge from the spatially correlated localized electrons in the flat bands of solid materials. By using scanning tunneling microscopy and spectroscopy (STM/STS), we report on the real-space investigation of correlated electrons in the flat band of superlattice 4⁢𝐻𝑏⁡−TaS⁢e𝑥⁢S2−𝑥. In contrast with the pristine 4⁢𝐻𝑏⁡−Ta⁢S2, the selenium (Se) substitutions significantly affect the interfacial transfer of correlated electrons between the charge density wave (CDW) states of 1⁢𝑇- and 1⁢𝐻⁡−Ta⁢S2 layers and contribute the real-space fractional electron-filling configurations with the distributed electron-filled and void Star of David (SoD) clusters of the 1⁢𝑇 layer. The site-specific STS spectra directly reveal their respective prominent spectra weight above 𝐸F and symmetric Mott-like spectra. In addition, the spatial distributions of these electron-filled SoDs in the 1⁢𝑇 layer of 4⁢𝐻𝑏⁡−TaS⁢e0.7⁢S1.3 demonstrate different local short-range order, clearly indicating the complex neighboring interactions among the localized electrons in the flat band of the 1⁢𝑇 layer. Our results not only provide in-depth insight into correlated electrons in the flat CDW band but also provide a simple platform to manipulate the electron-correlation-related quantum states.

Kagome bands and magnetism in MoTe2-x kagome monolayers

Kagome bands and magnetism in MoTe2-x kagome monolayers

Jiaqi Dai, Zhongqin Zhang, Zemin Pan, Cong Wang, Chendong Zhang*, Zhihai Cheng,  and Wei Ji*

Kagome lattices facilitate various quantum phases, yet in bulk materials, their kagome flat-bands often interact with bulk bands, suppressing kagome electronic characteristics for hosting these phases. Here, we use density-functional-theory calculations to predict the geometric and electronic structures, as well as the topological and magnetic properties, of a series of MoTe2-x kagome monolayers formed by mirror-twin-boundary (MTB) loops. We analyze nine MTB-loop configurations of varying sizes and arrangements to assess their impact on various properties. Within the intrinsic bandgap of MoTe2, we identify two sets of kagome bands, originating from in-plane and out-of-plane Te p-orbitals at MTB-loop edges and -vertices, respectively. Three configurations exhibit superior stability, while three others show comparable stability. Among these, four display bandgaps and potentially non-zero Z2 topological invariants, suggesting possible topological phases, while the remaining two are metallic and feature Stoner magnetization. These findings guide the design of kagome-based two-dimensional materials with tunable electronic, topological, and magnetic properties.

Nonvolatile Electric Control of Rashba Spin Splitting in Sb/In2Se3 Heterostructure

Nonvolatile Electric Control of Rashba Spin Splitting in Sb/In2Se3 Heterostructure

Haixia Cheng, Xu Sun, Jun Zhou*, Shijie Wang, Hang Su*, and Wei Ji*

Ferroelectric Rashba semiconductors (FRS) are highly demanded for their potential capability for nonvolatile electric control of electron spins. An ideal FRS is characterized by a combination of room temperature ferroelectricity and a strong Rashba effect, which has, however, been rarely reported. Herein, we designed a room-temperature FRS by vertically stacking a Sb monolayer on a room-temperature ferroelectric In2Se3 monolayer. Our first-principles calculations reveal that the Sb/In2Se3 heterostructure exhibits a clean Rashba splitting band near the Fermi level and a strong Rashba effect coupled to the ferroelectric order. Switching the electric polarization direction enhances the Rashba effect, and the flipping is feasible with a low energy barrier of 22 meV. This Rashba–ferroelectricity coupling effect is robust against changes of the heterostructure interfacial distance and external electric fields. Such a nonvolatile electrically tunable Rashba effect at room temperature enables potential applications in next-generation data storage and logic devices operated under small electrical currents.

杨紫尧 硕士生 Yang, Ziyao (M1 Student)

杨紫尧 硕士生 Yang, Ziyao (M1 Student)

基本信息
杨紫尧:2024级 硕士生
办公地点:北园物理楼206
电子邮箱:yangziyao@ruc.edu.cn
电  话:+86-10-62517997
传  真:+86-10-62517887
邮  编:100872

教育经历

(1) 2024-09 至今,中国人民大学,物理学系,硕士研究生,在读
(2) 2020-09至2024-06,东北师范大学,物理系,本科,理学学士

研究方向



代表性论文

冯佳佳 博士生 Feng, Jiajia (P1 Student)

冯佳佳 博士生 Feng, Jiajia (P1 Student)

基本信息
冯佳佳:2024级 直博生
办公地点:北园物理楼206
电子邮箱:fengjiajia@ruc.edu.cn
电  话:+86-10-62517997
传  真:+86-10-62517887
邮  编:100872

教育经历

(1) 2024-09 至今,中国人民大学,物理学系,直博,在读
(2) 2020-09 至 2024-06,山东师范大学,物理系,本科,理学学士

研究方向

层间耦合材料的第一性原理计算,氧化物材料的第一性原理计算。

代表性论文