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Magnetic moments of chiral phonons induced by coupling with magnons

Physical Review B 2024年第2期110卷 024423-024423页

作者： Qian Wang Meng-Qiu Long Yun-Peng Wang Hunan Key Laboratory for Super-Micro Structure and Ultrafast Process School of Physics Central South University

Chiral phonons composed of circular atomic motion possess a tiny magnetic moment as a result of the small g factor of ions. The couplings with the spin and orbit of electrons could entail a large magnetic moment. In this paper, we explore the possibility of an emergent phonon magnetic moment due to coupling with magnons in a hexagonal lattice. The magnetic moment of the phonon results from the mixture of magnon composition in the nonresonant coupling condition. Only one of the optical phonons gains a magnetic moment in the ferromagnetic case, while both phonon modes acquire a magnetic moment in the antiferromagnetic case. The magnon-induced magnetic moment of the phonon is proportional to the square of the magnon-phonon coupling strength. We also studied the case of nonequal atomic masses on sublattices which entails different magnetic moments of the two phonon modes.

关键词： Antiferromagnetism Ferromagnetism Magnetoelastic effect Magnons Phonons Spin-phonon coupling

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Trimetallic oxyhydroxides as active sites for large-current-density alkaline oxygen evolution and overall water splitting

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Journal of Materials Science & Technology 2022年第15期110卷 128-135页

作者： Lei Chen Yunpeng Wang Xin Zhao Yuchao Wang Qian Li Qichen Wang Yougen Tang Yongpeng Lei State Key Laboratory of Powder Metallurgy Hunan Key Laboratory of Two-Dimensional MaterialsCentral South UniversityChangsha 410083China Hunan Provincial Key Laboratory of Chemical Power Sources College of Chemistry and Chemical EngineeringCentral South UniversityChangsha 410083China School of Physics and Electronics Hunan Key Laboratory for Super-micro structure and Ultrafast ProcessCentral South UniversityChangsha 410083China

Earth-abundant electrocatalysts for large-current-density water splitting under alkaline condition are *** evolution reaction,which is a bottleneck of the overall water splitting,faces the problems of complicated reconstruction and deficiency in rational design of active ***,we report a series of transition metal chalcogenides for alkaline *** them,FeCoNi(S)displayed a low overpotential of 293 m V to deliver a current density of 500 m A cm^(-2),which is in the top level of non-precious metal based OER electrocatalysts.A combination of(ex)in situ characterizations and DFT calculation shows that Ni(Fe,Co)trimetallic oxyhydroxides were the active sites for highly-efficient ***,for FeCoNi(S),when used as a bifunctional catalyst for water splitting,it only required a cell voltage of 1.84 V to deliver~500 m A cm^(-2) with extraordinary long-term stability over 2000 *** work provides the comprehension of high-efficiency,robust catalysts for OER and overall water splitting at large current densities in alkaline media.

关键词： Oxygen evolution Active sites Surface reconstruction Large current density Overall water splitting

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Growth behaviors and emission properties of Co-deposited MAPbI_(3) ultrathin films on MoS_(2)

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Chinese Physics B 2023年第1期32卷 553-558页

作者：游思雯邵子依郭晓蒋俊杰刘金鑫王凯李明君欧阳方平邓楚芸宋飞孙家涛黄寒 Hunan Key Laboratory of Super-Microstructure and Ultrafast Process School of Physics and ElectronicsCentral South UniversityChangsha 410083China College of Arts and Science National University of Defense TechnologyChangsha 410073China Key Laboratory of Interfacial Physics and Technology Shanghai Institute of Applied PhysicsChinese Academy of SciencesShanghai 201000China School of Information and Electronics MIIT Key Laboratory for Low-Dimensional Quantum Structure and DevicesBeijing Institute of TechnologyBeijing 100081China

Hybrid organic–inorganic perovskite thin films have attracted much attention in optoelectronic and information fields because of their intriguing properties. Due to quantum confinement effects, ultrathin films in nm scale usually show special properties. Here, we report on the growth of methylammonium lead iodide(MAPbI_(3)) ultrathin films via co-deposition of PbI_2 and CH_3NH_3I(MAI) on chemical-vapor-deposition-grown monolayer MoS_(2) as well as the corresponding photoluminescence(PL) properties at different growing stages. Atomic force microscopy and scanning electron microscopy measurements reveal the MoS_(2) tuned growth of MAPbI_(3) in a Stranski–Krastanov mode. PL and Kelvin probe force microscopy results confirm that MAPbI_(3) /MoS_(2) heterostructures have a type-Ⅱ energy level alignment at the interface. Temperaturedependent PL measurements on layered MAPbI_(3) (at the initial stage) and on MAPbI_(3) crystals in averaged size of 500 nm(at the later stage) show rather different temperature dependence as well as the phase transitions from tetragonal to orthorhombic at 120 and 150 K, respectively. Our findings are useful in fabricating MAPbI_(3) /transition-metal dichalcogenide based innovative devices for wider optoelectronic applications.

关键词： MAPbI_(3)/MoS_(2)heterostructure Co-deposition temperature-dependent photoluminescence growth behavior

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First-principles study of spin-orbital coupling induced ferroelectricity in NiBr2

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Physical Review B 2023年第5期108卷 054429-054429页

作者： Da-Wei Wu Yong-Bo Yuan Shuang Liu Meng-Qiu Long Yun-Peng Wang School of Physics and Electronics Hunan Key Laboratory for Super-Micro Structure and Ultrafast Process Central South University 932 South Lushan Road Changsha 410083 People's Republic of China

Two-dimensional multiferroic materials have attracted wide interest due to their intriguing physical properties and strong electromagnetic coupling. Among them, NiBr2 is unique with a temperature dependent magnetic modulation vector Q which is linearly related to the electric polarization. In this work, we perform first-principles calculations on the NiBr2 monolayer. Density functional theory calculations with appropriate Hubbard correction reproduce the electric polarization and its linear dependence on the magnitude of Q. The calculated polarization decreases as the Hubbard parameter U increases which enlarges the electronic band gap. Our results suggest the spin-orbital coupling effect of Br ions play a crucial role in generating the polarization. Wannier function analysis proves that the major contributor to electric polarization is the Br atomic orbitals which are strongly hybridized with Ni orbitals. The atomic position relaxation has a negligible contribution to the polarization.

关键词： Ferroelectricity Multiferroics Noncollinear magnets Density functional calculations

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Defects in ultraflat germanene on Cu(111)

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Physical Review B 2024年第12期110卷 125430页

作者： Qiwei Tian Xiao Guo Sahar Izadi Vishkayi Meysam Bagheri Tagani Li Zhang Yuan Tian Long-Jing Yin Han Huang Lijie Zhang Zhihui Qin Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices School of Physics and Electronics Hunan Key Laboratory of Super-microstructure and Ultrafast Process School of Physics School of Physics Department of Physics

Germanene is one of the most promising two-dimensional materials beyond graphene. The electronic properties of germanene are outstanding. However, structural defects, which may appear during growth or processing, deteriorating the performance of germanene-based devices, are elusive. Here, we combine scanning tunneling microscopy/spectroscopy, Raman spectroscopy, and density functional theory calculations to investigate the defects in epitaxial ultraflat germanene on Cu(111). Three types of defects are found and their electronic properties are explored. Single germanium atom vacancy leads to three well-defined states in local density of states, whereas the mirror twin boundary induced four electronic states confirmed by theoretical calculations. Furthermore, strain induced wrinkles with enhanced electronic states occurred in ultraflat germanene. In addition, we synthesized bi- and trilayer germanene with significant different electronic properties, where a tiny band gap is opened due to the symmetry breaking.

关键词： Germanene Density functional theory Scanning tunneling microscopy Scanning tunneling spectroscopy

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A first-principles study on zigzag phosphorene nanoribbons terminated by transition metal atoms

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Chinese Physics B 2021年第2期30卷 476-480页

作者： Shuai Yang Zhiyong Wang Xueqiong Dai Jianrong Xiao Mengqiu Long College of Science Guilin University of TechnologyGuilin 541008China Modern Education Technology Center Guilin University of TechnologyGuilin 541008China Hunan Key Laboratory of Super Micro-structure and Ultrafast Process Central South UniversityChangsha 410083China

We have investigated the electronic and magnetic properties of zigzag phosphorene nanoribbons(ZPNRs)with transition metal(TM)passivated atoms,it can be found that the ZPNRs with TM passivated atoms exhibit different magnetisms except for the Ni-passivated ***,the results show that the magnetic moments of ZPNRs with TM passivated atoms are larger than that of ZPNRs with other passivated non-metals/***,it can be found that Fe-passivated ZPNR exhibits magnetic semiconducting character,which provides the possbility for the application of phosphorene in information *** Mn-passivated ZPNRs,it exhibits the *** results may be useful for potential applications of phosphorene in electronic and high-performance spintronic devices.

关键词： phosphorene first-principles calculations half-metallicity passivated

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Controlled growth of transition metal dichalcogenide via ther-mogravimetric prediction of precursors vapor concentration

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Nano Research 2021年第8期14卷 2867-2874页

作者： Long Fang Shaohua Tao Zhenzhen Tian Kunwu Liu Xi Li Jiang Zhou Han Huang Jun He Xiaoming Yuan Hunan Key Laboratory of Super Micro-structure and Ultrafast Process School of Physics and ElectronicsCentral South UniversityChangsha 410083China School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410004China School of Materials Science and Engineering Central South University Changsha 410083China

Transition metal dichalcogenide(TMD)alloys and heterostructures are attracting increasing attention thanks to their unique electronic,optical,and interfacial ***,the growth fundamental of TMD alloys and heterostructures during one-step growth is still beyond ***,thermogravimetric(TG/DTG)technology is introduced to predict the evolution of the precursor(MoO_(3)and WO_(3))concentration in the vapor during *** establish the correlation between precursor concentration and the corresponding growth ***/DTG predication suggests that tuning precursor temperature and powder ratio can alter their concentration in the vapor,well explaining the formation of Mo_(x)W_(1-x)Se_(2) alloy or MoSe_(2)-WSe_(2) heterostructure at different growth *** on the TG/DTG analysis,we further design and grow a complex MoSe_(2)-Mo_(x)W_(1-x)Se_(2)-WSe_(2) heterostructure and Mo_(x)W_(1-x)Se_(2) monolayer alloys,confirming the validity of TG/DTG prediction in TMD crystal ***,employing TG/DTG to predict the synthesis of two-dimensional materials is of importance to understand the TMD growth behavior and provide guidance to the desired TMD heterostructure formation for future photoelectric devices.

关键词： TG/DTG Mo_(x)W_(1-x)Se_(2)alloys MoSe_(2)-WSe_(2)lateral heterostructures precursor concentration

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First-Principles investigation of the First-order Phase Transition in Kagome Na2Ti3Cl8

arXiv

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arXiv 2022年

作者： Liu, Shuang Yin, Zhi-Bo Long, Meng-Qiu Wang, Yun-Peng School of Physics and Electronics Hunan Key Laboratory for Super-micro structure and Ultrafast Process Central South University 932 South Lushan Road Changsha China

The antiferromagnetic kagome material Na2Ti3Cl8 exhibits a first-order phase transition;the low-temperature phase is characterized by the trimerizations of Ti ions. In this work, we carry out first-principles calculations on the crystal and electronic structure of Na2Ti3Cl8 at the high- and low-temperature phases. The crystal structures, including the lattice constant and the trimerization of Ti ions, are well reproduced by taking account a small Hubbard correction of 1 eV. The calculated total energy landscape reveals a first-order phase transition with the total energy barrier of 80 meV per formula unit. Analysis of the electronic structure indicates a direct metal bonding among Ti in the trimierized low-temperature phase. © 2022, CC0.

关键词： Sodium compounds

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Stress compensation based on interfacial nanostructures for stable perovskite solar cells

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Interdisciplinary Materials 2023年第2期2卷 348-359页

作者： Cheng Zhu Xi Wang Hangxuan Li Chenyue Wang Ziyan Gao Pengxiang Zhang Xiuxiu Niu Nengxu Li Zipeng Xu Zhenhuang Su Yihua Chen Huachao Zai Haipeng Xie Yizhou Zhao Ning Yang Guilin Liu Xueyun Wang Huanping Zhou Jiawang Hong Xingyu Gao Yang Bai Qi Chen Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications MIIT Key Laboratory for Lowdimensional Quantum Structure and DevicesExperimental Center of Advanced MaterialsSchool of Materials Science and EngineeringBeijing Institute of TechnologyBeijingChina School of Aerospace Engineering Beijing Institute of TechnologyBeijingChina Department of Materials Science and Engineering College of EngineeringPeking UniversityBeijingChina Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghaiChina Hunan Key Laboratory for Super-microstructure and Ultrafast Process School of Physics and ElectronicsCentral South UniversityChangshaChina School of Science Jiangnan University WuxiWuxiJiangsuChina

The long-term stability issue of halide perovskite solar cells hinders their *** residual stress-strain affects device stability,which is derived from the mismatched thermophysical and mechanical properties between adjacent *** this work,we introduced the Rb_(2)CO_(3)layer at the interface of SnO_(2)/perovskite with the hierarchy morphology of snowflake-like microislands and dendritic *** a suitable thermal expansion coefficient,the Rb_(2)CO_(3)layer benefits the interfacial stress relaxation and results in a compressive stress-strain in the perovskite ***,reduced nonradiative recombination losses and optimized band alignment were *** enhancement of open-circuit voltage from 1.087 to 1.153 V in the resultant device was witnessed,which led to power conversion efficiency(PCE)of 22.7%(active area of 0.08313 cm^(2))and 20.6%(1 cm2).Moreover,these devices retained 95%of its initial PCE under the maximum power point tracking(MPPT)after 2700 *** suggests inorganic materials with high thermal expansion coefficients and specific nanostructures are promising candidates to optimize interfacial mechanics,which improves the operational stability of perovskite cells.

关键词： interfacial nanostructures long-term stability perovskite solar cells strain engineering thermal expansion coefficient

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Effects of 3d-transition metal doping on the electronic and magnetic properties of one-dimensional diamond nanothread

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Chinese Physics B 2020年第6期29卷 358-363页

作者： Zhenzhen Miao Can Cao Bei Zhang Haiming Duan Mengqiu Long Institute of Low-dimensional Quantum Materials and Devices School of Physics Science and TechnologyXinjiang UniversityUrumqi 830046China Hunan Key Laboratory of Super Micro-structure and Ultrafast Process School of Physics and ElectronicsCentral South UniversityChangsha 410083China

The diamond nanothread(DNT), a new one-dimensional(1 D) full carbon sp3 structure that has been successfully synthesized recently, has attracted widespread attention in the carbon community. By using the first-principles calculation method of density functional theory(DFT), we have studied the effects of 3 d transition metal(TM) atomic doping on the electronic and magnetic properties of DNT. The results show that the spin-polarized semiconductor characteristics are achieved by doping Sc, V, Cr, Mn, and Co atoms in the DNT system. The magnetic moment ranges from 1.00 μB to 3.00 μB and the band gap value is from 0.35 e V to 2.54 e V. The Fe-doped DNT system exhibits spin-metallic state with a magnetic moment of 2.58 μB, while the Ti and Ni-doped DNT systems are nonmagnetic semiconductors. These results indicate that the 3 d TM atoms doping can modulate the electronic and magnetic properties of 1 D-DNT effectively, and the TM-doped DNT systems have potential applications in the fields of electronics, optoelectronics, and spintronics.

关键词： diamond nanothread transition metal atom doping electronic and magnetic property

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