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First-principles study of electronic and magnetic properties of Fe atoms on Cu_(2)N/Cu(100)

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Chinese physics B 2024年第8期33卷 498-503页

作者：陈佳乐胡军 Institute of high pressure physics School of Physical Science and TechnologyNingbo UniversityNingbo 315211China

First-principles calculations were conducted to investigate the structural,electronic,and magnetic properties of single Fe atoms and Fe dimers on Cu_(2)N/Cu(100).Upon adsorption of an Fe atom onto Cu_(2)N/Cu(100),robust Fe-N bonds form,resulting in the incorporation of both single Fe atoms and Fe dimers within the surface Cu_(2)N *** partial occupancy of Fe-3d orbitals lead to large spin moments on the Fe ***,both single Fe atoms and Fe dimers exhibit in-plane magnetic anisotropy,with the magnetic anisotropy energy(MAE)of an Fe dimer exceeding twice that of a single Fe *** magnetic anisotropy can be attributed to the predominant contribution of the component along the x direction of the spin-orbital coupling ***,the formation of Fe-Cu dimers may further boost the magnetic anisotropy,as the energy levels of the Fe-3d orbitals are remarkably influenced by the presence of Cu *** study manifests the significance of uncovering the origin of magnetic anisotropy in engineering the magnetic properties of magnetic nanostructures.

关键词： magnetic nanostructures magnetic anisotropy spin–orbital coupling ultrathin substrate

Synthesis and nitrogen content regulation of diamond in a high-pressure hydrogen-rich environment

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Chinese physics B 2024年第6期33卷 541-546页

作者：黄国锋陈良超房超 Inner Mongolia Key laboratory of high-pressure Phase Functional Materials Chifeng UniversityChifeng 024000China Key laboratory of Material physics of Ministry of Education School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China

The regulating nitrogen content of diamond in a hydrogen-rich high-temperature and high-pressure(HPHT) growth environment was systematically investigated in this work by developing three growth systems,namely, "FeNi+Ti", "FeNi+G_(3)N_(6)H_(6)",and "FeNi+Ti+C_(3)N_(6)H_(6)".Optical microscopy,infrared spectroscopy,and photoluminescence(PL)spectroscopy measurements were conducted to analyze the spectroscopic characteristics of diamonds grown in these three *** our analysis,it was demonstrated that the presence of hydrogen in the sp^(3) hybrid C-H does not directly affect the color of the diamond and facilitates the increase of the nitrogen-vacancy(NV) center concentration in a highnitrogen-content *** addition,titanium plays an important role in nitrogen removal,while its impact on hydrogen doping within the diamond lattice is *** importantly,by regulating the ratio of nitrogen impurities that coexist in the nitrogen and hydrogen HPHT environment,the production of hydrogenous Ⅱa-type diamond,hydrogenous Ib-type diamond,and hydrogenous high-nitrogen-type diamonds was achieved with a nitrogen content of less than 1 ppm to 1600 ppm.

关键词： diamond HPHT superhard material hydrogen-rich environment

Unveiling the pressure-driven metal–semiconductor–metal transition in the doped TiS_(2)

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Chinese physics B 2024年第6期33卷 63-67页

作者：陈佳骏吕心邓李思敏但雅倩黄艳萍崔田 Institute of high pressure physics School of Physical Science and TechnologyNingbo UniversityNingbo 315211China State Key laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China

Conventional theories expect that materials under pressure exhibit expanded valence and conduction bands,leading to increased electrical ***,we report the electrical properties of the doped 1T-TiS_(2) under high pressure by electrical resistance investigations,synchrotron x-ray diffraction,Raman scattering and theoretical *** to 70 GPa,an unusual metal-semiconductor-metal transition *** first-principles calculations suggest that the observed anti-Wilson transition from metal to semiconductor at 17 GPa is due to the electron localization induced by the intercalated Ti *** electron localization is attributed to the strengthened coupling between the doped Ti atoms and S atoms,and the Anderson localization arising from the disordered *** pressures exceeding 30.5 GPa,the doped TiS_(2) undergoes a re-metallization transition initiated by a crystal structure phase *** assign the most probable space group as P2_(1)2_(1)2_(1).Our findings suggest that materials probably will eventually undergo the Wilson transition when subjected to sufficient pressure.

关键词： high pressure transition metal dichalcogenides doped TiS_(2) electronic phase transition

Strong electron correlation-induced Mott-insulating electrides of Ae_(5)X_(3)(Ae=Ca,Sr,and Ba;X=As and Sb)

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Matter and Radiation at Extremes 2024年第3期9卷 74-82页

作者： Ya Xu Lu Zheng Yunkun Zhang Zhuangfei Zhang QianQian Wang Yuewen Zhang Liangchao Chen Chao Fang Biao Wan Huiyang Gou Key laboratory of Material physics of Ministry of Education School of Physics and Laboratory of Zhongyuan LightZhengzhou UniversityZhengzhou 450052China School of Mechanical and Equipment Engineering Hebei University of EngineeringHandan 056038China Center for high pressure Science and Technology Advanced Research Beijing 100094China

The presence of interstitial electrons in electrides endows them with interesting attributes,such as low work function,high carrier concentration,and unique magnetic *** knowledge and understanding of electrides are thus of both scientific and technological ***,we employ first-principles calculations to investigate Mott-insulating Ae_(5)X_(3)(Ae=Ca,Sr,and Ba;X=As and Sb)electrides with Mn_(5)Si_(3)-type structure,in which half-filled interstitial electrons serve as ions and are *** Mott-insulating property is induced by strong electron correlation between the nearest interstitial electrons,resulting in spin splitting and a separation between occupied and unoccupied *** half-filled antiferromagnetic configuration and localization of the interstitial electrons are critical for the Mott-insulating properties of these *** with that in intermetallic electrides,the orbital hybridization between the half-filled interstitial electrons and the surrounding atoms is weak,leading to highly localized magnetic centers and pronounced correlation ***,the Mott-insulating electrides Ae_(5)X_(3)have very large indirect bandgaps(0.30 eV).In addition,high pressure is found to strengthen the strong correlation effects and enlarge the *** present results provide a deeper understanding of the formation mechanism of Mott-insulating electrides and provide guidance for the search for new strongly correlated electrides.

关键词： intermetallic filled occupied

A novel method for determining the resistivity of compressed superconducting materials

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Matter and Radiation at Extremes 2024年第4期9卷 1-3页

作者： Liling Sun Qi Wu Shu Cai Yang Ding Ho-kwang Mao Center for high pressure Science and Technology Advanced Research Beijing 100094China Institute of physics Chinese Academy of SciencesBeijing 100190China

The measurement of resistivity in a compressed material within a diamond anvil cell presents significant *** high-pressure exper-imental setup makes it difficult to directly measure the size changes induced by pressure in the three crystallographic directions of the *** this study,we introduce a novel and effective method that addresses these technical *** method is anticipated to offer a valuable foundation for high-pressure investigations on quantum materials,particularly those with anisotropic layered structures.

关键词： resistivity method foundation

Coevolution of superconductivity and Hall coefficient with anisotropic lattice shrinkage in compressed KCa_(2)Fe_(4)As_(24F_(2)

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Chinese physics B 2024年第7期33卷 66-70页

作者：韩金宇洪文山蔡树赵金瑜郭静周亚洲王鹏玉曹立新罗会仟李世亮吴奇孙力玲 Beijing National laboratory for Condensed Matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Center for high pressure Science&Technology Advanced Research Beijing 100094China University of Chinese Academy of Sciences Beijing 100190China

The stability of superconductivity in superconductors is widely recognized to be determined by various factors,including charge,spin,orbit,lattice,and other related degrees of ***,we report our findings on the pressure-induced coevolution of superconductivity and Hall coefficient in KCa_(2)Fe_(4)As_(24F_(2),an iron-based superconductor possessing a hybrid crystal structure combining KFe_(2)As_(2) and *** investigation,involving high-pressure resistance,Hall effect and x-ray diffraction(XRD) measurements,allows us to observe the connection of the superconductivity and Hall coefficient with the anisotropic lattice *** find that its ambient-pressure tetragonal(T) phase presents a collapse starting at around 18 GPa,where the sign of the Hall coefficient(R_(H)) changes from positive to *** further compression,both superconducting transition temperature(T_(c)) and R_(H) exhibit a monotonous *** around 41 GPa,the superconductivity is completely suppressed(T_(c)=0),where the parameter a begins to decline again and the Hall coefficient remains nearly *** experiment results clearly demonstrate that the pressure-induced anisotropic lattice collapse plays a crucial role in tuning the interplay among multiple degrees of freedom in the superconducting system and,correspondingly,the stability of the superconductivity.

关键词： effects of pressure pnictides and chalcogenides transport properties

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Ultrafast investigation of room temperature valley polarization in“optical bilayer”WS_(2)

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Science China(Technological Sciences) 2024年第1期67卷 91-97页

作者： ZHAO LeYi WANG Hai LIU TianYu LI FangFei ZHOU Qiang WANG HaiYu Synergetic Extreme Condition high-pressure Science Center State Key Laboratory of Superhard MaterialsCollege of PhysicsJilin UniversityChangchun 130012China State Key laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

Monolayer transition metal dichalcogenides(TMDCs)have become a promising platform in valleytronics due to possessing the regulatable valley degrees of ***,as a result of the rapid intervalley scattering,it is difficult to measure the PL valley polarization of monolayer TMDCs at room temperature,which limits their application in valleytronics ***,we report a room temperature photoluminescence(PL)valley polarization up to 3.73%in an“optical bilayer”WS_(2)formed by transferring monolayer WS_(2)onto flat Ag ***,in the transient absorption(TA)measurements,a remarkably long valley depolarization lifetime is ***,we demonstrate the valley properties of such“optical bilayer”WS_(2)resemble actual bilayer WS_(2),in which the robust valley polarization can be attributed to the phonons depletion effect and the blocked interlayer hopping *** peculiar valley features in“optical bilayer”WS_(2)provide a particularly simple method to enhance valley control at room temperature.

关键词： valleytronics optical bilayer transient absorption tungsten disulfide

Unveiling a novel metal-to-metal transition in LuH_(2):Critically challenging superconductivity claims in lutetium hydrides

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Matter and Radiation at Extremes 2024年第3期9卷 65-73页

作者： Dong Wang Ningning Wang Caoshun Zhang Chunsheng Xia Weicheng Guo Xia Yin Kejun Bu Takeshi Nakagawa Jianbo Zhang Federico Gorelli Philip Dalladay-Simpson Thomas Meier Xujie Lü Liling Sun Jinguang Cheng Qiaoshi Zeng Yang Ding Ho-kwang Mao Center for high-pressure Science and Technology Advanced Research Beijing 100094China Beijing National laboratory for Condensed Matter physics and Institute of physics Chinese Academy of SciencesBeijing 100190China Shanghai Key laboratory of Material Frontiers Research in Extreme Environments(MFree) Shanghai Advanced Research in Physical Sciences(SHARPS)Shanghai 201203China

Following the recent report by Dasenbrock-Gammon et al.[Nature 615,244–250(2023)]of near-ambient superconductivity in nitrogendoped lutetium trihydride(LuH_(3-δ)N_(ε)),significant debate has emerged surrounding the composition and interpretation of the observed sharp resistance ***,we meticulously revisit these claims through comprehensive characterization and *** definitively identify the reported material as lutetium dihydride(LuH_(2)),resolving the ambiguity surrounding its *** similar conditions(270–295 K and 1–2 GPa),we replicate the reported sharp decrease in electrical resistance with a 30%success rate,aligning with the observations by Dasenbrock-Gammon et ***,our extensive investigations reveal this phenomenon to be a novel pressure-induced metal-to-metal transition intrinsic to LuH_(2),distinct from ***,nitrogen doping exerts minimal impact on this *** work not only elucidates the fundamental properties of LuH_(2)andLuH_(3),but also critically challenges the notion of superconductivity in these lutetium hydride *** findings pave the way for future research on lutetium hydride systems,while emphasizing the crucial importance of rigorous verification in claims of ambient-temperature superconductivity.

关键词： resistance hydride superconductivity

Stability and melting behavior of boron phosphide under high pressure

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Chinese physics B 2024年第4期33卷 579-584页

作者：梁文嘉向晓君李倩梁浩彭放 Institute of Atomic and Molecular physics Sichuan UniversityChengdu 610065China School of Mathematics and physics Southwest University of Science and TechnologyMianyang 621900China Center for high pressure Science and Technology Advanced Research Shanghai 201203China

Boron phosphide(BP)has gained significant research attention due to its unique photoelectric and mechanical *** this work,we investigated the stability of BP under high pressure using x-ray diffraction and scanning electron *** phase diagram of BP was explored in both B-rich and P-rich environments,revealing crucial insight into its behavior at 5.0 ***,we measured the melting curve of BP from 8.0 GPa to 15.0 *** findings indicate that the stability of BP under high pressure is improved within B-rich and P-rich ***,we report a remarkable observation of melting curve frustration at 10.0 *** study will enhance our understanding of stability of BP under high pressure,shedding light on its potential application in semiconductor,thermal,and light-transmitting devices.

关键词： boron phosphide stability melting curve high pressure