Search

Your search keyword '"Ren, Ji-Chang"' showing total 127 results
Start Over Author "Ren, Ji-Chang"
127 results on '"Ren, Ji-Chang"'

6. Origin of unexpected large Seebeck effect in SrTiO3: nonperturbative polaron study from ab initio cumulant expansion

Author

Ren, Ji-Chang and Wang, Jian-Sheng

Subjects
Condensed Matter - Materials Science
Abstract

The experimental unexpected large Seebeck coefficient in SrTiO3 (STO) cannot be reproduced theoretically by the conventional Bloch-Boltzmann transport with electron-phonon coupling calculated perturbatively, indicating a failure of Fermi liquid picture in STO and ill-treatment of polaronic states. Starting from many-body interaction picture, the polaronic states can be precisely described by the method of cumulant expansion of retarded Green's function. By applying Kubo-Greenwood method, we found that the mysterious Seebeck coefficient can be fully described by a combination of polarons and Fermi liquid. The coexistence of two types of quasi-particles are attributed to the multi-band nature of t2g orbitals. Polarons are formed from the one with heavier electronic effective mass, while the one with lighter effective mass is renormalized into Fermi liquid quasi-particles. Our method provides a practical way to study the effect of strong electron-phonon coupling on transport properties from first principles., Comment: 6 pages, 5 figures

Published
2018

7. Phonon-Driven Electron Scattering and Magnetothermoelectric Effect in Two-Dimensional Tin Selenide

Author

Yang, Kaike, Ren, Ji-Chang, Qiu, Hongfei, and Wang, Jian-Sheng

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The bulk tin selenide (SnSe) is the best thermoelectric material currently with the highest figure-of-merit due to the strong phonon-phonon interactions. We investigate the effect of electron-phonon coupling (EPC) on the transport properties of two-dimensional (2D) SnSe sheet. We demonstrate that EPC plays a key role in the scattering rate where the constant relaxation time approximation is deficient. The EPC strength is especially large in contrast to that of pristine graphene. The scattering rate depends sensitively on the system temperatures and the carrier densities when the Fermi energy approaches the band edge. We also investigate the magnetothermoelectric effect of the 2D SnSe. It is found that at low temperatures there are enormous magnetoelectrical resistivity and magnetothermal resistivity above 500\%, suggesting the high potential for device applications. Our results agree reasonably well with the experimental data., Comment: 9 pages, 4 figures

Published
2017
Full Text
View/download PDF

8. Strong Electron-Phonon Interaction and Colossal Magnetoresistance in EuTiO$_3$

Author

Chen, Ruofan, Ren, Ji-Chang, Rubi, Km, Mahendiran, R., and Wang, Jian-Sheng

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

At low temperatures, EuTiO$_3$ system has very large resistivities and exhibits colossal magnetoresistance. Based on a first principle calculation and the dynamical mean-field theory for small polaron we have calculated the transport properties of EuTiO$_3$. It is found that due to electron-phonon interaction the conduction band may form a tiny subband which is close to the Fermi level. The tiny subband is responsible for the large resistivity. Besides, EuTiO$_3$ is a weak antiferromagnetic material and its magnetization would slightly shift the subband via exchange interaction between conduction electrons and magnetic atoms. Since the subband is close to the Fermi level, a slight shift of its position gives colossal magnetoresistance., Comment: 6 pages, 5 figures

Published
2017
Full Text
View/download PDF

9. An Efficient Descriptor for Rapid Determination of Dipole Moments and Band Alignments of 2D Janus Transition‐Metal Dichalcogenides.

Author

Liu, Jia, Shen, Tao, Wang, Linghui, Ren, Ji‐Chang, Liu, Wei, and Li, Shuang

Subjects
KELVIN probe force microscopy, DIPOLE moments, ATOMIC number, ATOMIC radius, ATOMIC structure
Abstract

The dipole moment (µ) is a critical parameter in Janus structures, influencing band alignments and carrier transmissions. However, evaluating µ in 2D Janus layers is challenging due to the vast number of structures and the inefficiency of Kelvin probe force microscopy. Using the recently developed 2D Janus transition‐metal dichalcogenides (TMDCs) as a prototype, a descriptor is proposed based on fundamental parameters (atomic number and atomic radii) to investigate the relationship between atomic structures and µ. By constructing 621 structural models, this descriptor is applicable from monolayers to three‐layers. By considering shielding effect of terminal atoms, the performance of the descriptor has been significantly enhanced, resulting in a description accuracy of 94.6% for all TMDC systems. Based on this descriptor, the Anderson's Rule (AR) model can be extended to Janus bilayers in simulating band alignments, resulting in a substantial improvement in accuracy from 20.0% to 90.8%. This development holds crucial importance in screening Janus self‐doping P‐N junctions. The work provides an efficient descriptor based on inherent atomic properties for rapid determining dipole moment and band alignment in 2D Janus TMDCs, accelerating the design of devices with built‐in electronic field structures. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

28. External strain-enhanced cysteine enantiomeric separation ability on alloyed stepped surfaces.

Author

Li, Meng, Yang, Sha, Chen, Chao, Ren, Ji-Chang, Fuentes-Cabrera, Miguel, Li, Shuang, and Liu, Wei

Subjects
METALLIC surfaces, CYSTEINE, PHARMACEUTICAL technology, DENSITY functional theory, SEPARATION (Technology), BINDING energy
Abstract

Using density functional theory with an accurate treatment of van der Waals interactions, we investigate the enantioselective recognition and separation of chiral molecules on stepped metal surfaces. Our calculations demonstrate that the separation ability of metal substrates can be significantly enhanced by surface decoration and external strain. For example, applying 2% tensile strain to the Ag-alloyed Au(532) surface leads to a dramatic increase (by 89%) in cysteine enantioselectivity as compared to that of pristine Au(532). Analysis on the computed binding energies shows that the interaction energy is the predominant factor that affects the separation efficiency in strongly bound systems. Our study presents a new strategy to modify the enantioselectivity of stepped metal surfaces and paves the way for exploring high efficiency chiral separation technology in pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

34. Discovery of New Metallic and Superconducting Phase in GaTa4Se8 Under High Pressure

Author

Deng, Hongshan, primary, Zhang, Jianbo, additional, Jeong, Min Yong, additional, Sereika, Raimundas, additional, Wang, Dong, additional, Nakagawa, Takeshi, additional, Chen, Bijuan, additional, Yin, Xia, additional, Ren, Ji-Chang, additional, Han, Myung Joon, additional, Chang, Jun, additional, Weng, Hongming, additional, Ding, Yang, additional, and Mao, Ho-Kwang, additional

Published
2020
Full Text
View/download PDF

44. An asymmetric Ti2CO/WS2 heterostructure as a promising anchoring material for lithium–sulfur batteries.

Author

Fang, Qin, Fang, Min, Liu, Xinyi, Yu, Pengfei, Ren, Ji-Chang, Li, Shuang, and Liu, Wei

Abstract

The practical applications of lithium–sulfur (Li–S) batteries are greatly hindered by their low cycling stability and low efficiency, which mainly stem from the dissolution and diffusion of lithium polysulfides in the electrolyte. To tackle these challenges, here we construct an asymmetric polar Ti2CO/WS2 heterostructure to simultaneously trap lithium polysulfides and accelerate reaction kinetics. Van der Waals inclusive density-functional theory computations are carried out to uncover the unique role of the asymmetric heterostructure in the enhancement of the performance of Li–S batteries. In particular, we find higher adsorption energies of high-order lithium polysulfides on the O-terminal side, which helps to restrain the shuttle effect in Li–S batteries. Meanwhile, the S-terminal side of the heterostructure possesses a lower diffusion barrier and decomposition barrier, being specifically favorable for fast electrochemical processes. The analysis of the density of states of Ti2CO/WS2 shows the metallic character of the system; this guarantees the high conductivity and fast electron transfer of the proposed electrode. All these features illustrate that such asymmetric heterostructures could be promising anchoring materials for advanced Li–S batteries. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

49. Conductance Switching in Molecular Self-Assembled Monolayers for Application of Data Storage

Author

Chen, Chao, Yang, Sha, Su, Guirong, Li, Jingtai, Ren, Ji-Chang, and Liu, Wei

Abstract

By carrying out dispersion-inclusive density-functional theory computations, we propose a novel type of molecular memory based on the physisorbed and chemisorbed states of a layer of aromatic molecules on metal surfaces. As exemplified by hexachlorobenzene (C6Cl6) on Pt(111), we find that the self-assembled monolayer exhibits an intriguing bistable behavior: molecules can stay stable in either the physiosorbed state (“1”) or the chemisorbed state (“0”), along with a moderate switching barrier. Correspondingly, our transport computations based on the nonequilibrium Green’s function uncover a distinct conductance switching behavior of the molecular layer at the two states. Finally, we determine the thermal stability of the well-defined arrays and demonstrate the feasibility of using a molecule as a bit in an ordered pattern.

Published
2021
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results