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A unified theory of ferromagnetic quantum phase transitions in heavy fermion metals

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Science China(Physics,Mechanics & Astronomy) 2022年第5期65卷 104-113页

作者： Jiangfan Wang yi-feng yang Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of ScienceBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China

Motivated by the recent discovery of a continuous ferromagnetic quantum phase transition in Ce Rh_(6)Ge_(4) and its distinction from other U-based heavy fermion metals such as UGe_(2),we develop a unified explanation of their different ground state properties based on an anisotropic ferromagnetic Kondo-Heisenberg model.We employ an improved large-N Schwinger boson approach and predict a full phase diagram containing both a continuous ferromagnetic quantum phase transition for large magnetic anisotropy and first-order transitions for relatively small anisotropy.Our calculations reveal three different ferromagnetic phases including a half-metallic spin selective Kondo insulator with a constant magnetization.The Fermi surface topologies are found to change abruptly between different phases,consistent with that observed in UGe_(2).At finite temperatures,we predict the development of Kondo hybridization well above the ferromagnetic long-range order and its relocalization near the phase transition,in good agreement with band measurements in Ce Rh_(6)Ge_(4).Our results highlight the importance of magnetic anisotropy and provide a unified theory for understanding the ferromagnetic quantum phase transitions in heavy fermion metals.

关键词： ferromagnetic Kondo lattice magnetic anisotropy ferromagnetic quantum phase transition Schwinger boson

Spectroscopic data de-noising via training-set-free deep learning method

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Science China(Physics,Mechanics & Astronomy) 2023年第6期66卷 191-199页

作者： Dongchen Huang Junde Liu Tian Qian yi-feng yang Beijing National Laboratoryfor Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China

De-noising plays a crucial role in the post-processing of spectra.Machine learning-based methods show good performance in extracting intrinsic information from noisy data,but often require a high-quality training set that is typically inaccessible in real experimental measurements.Here,using spectra in angle-resolved photoemission spectroscopy(ARPES)as an example,we develop a de-noising method for extracting intrinsic spectral information without the need for a training set.This is possible as our method leverages the self-correlation information of the spectra themselves.It preserves the intrinsic energy band features and thus facilitates further analysis and processing.Moreover,since our method is not limited by specific properties of the training set compared with previous ones,it may well be extended to other fields and application scenarios where obtaining high-quality multidimensional training data is challenging.

关键词： de-noising deep learning spectroscopic data

Dynamic prediction of moving trajectory in pipe jacking: GRU-based deep learning framework

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Frontiers of Structural and Civil Engineering 2023年第7期17卷 994-1010页

作者： yi-feng yang Shao-Ming LIAO Meng-Bo LIU Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Key Laboratory of Road and Traffic Engineering of Ministry of Education Tongji UniversityShanghai 201804China

The moving trajectory of the pipe-jacking machine(PJM),which primarily determines the end quality of jacked tunnels,must be controlled strictly during the entire jacking process.Developing prediction models to support drivers in performing rectifications in advance can effectively avoid considerable trajectory deviations from the designed jacking axis.Hence,a gated recurrent unit(GRU)-based deep learning framework is proposed herein to dynamically predict the moving trajectory of the PJM.In this framework,operational data are first extracted from a data acquisition system;subsequently,they are preprocessed and used to establish GRU-based multivariate multistep-ahead direct prediction models.To verify the performance of the proposed framework,a case study of a large pipe-jacking project in Shanghai and comparisons with other conventional models(i.e.,long short-term memory(LSTM)network and recurrent neural network(RNN))are conducted.In addition,the effects of the activation function and input time-step length on the prediction performance of the proposed framework are investigated and discussed.The results show that the proposed framework can dynamically and precisely predict the PJM moving trajectory during the pipe-jacking process,with a minimum mean absolute error and root mean squared error(RMSE)of 0.1904 and 0.5011 mm,respectively.The RMSE of the GRU-based models is lower than those of the LSTM-and RNN-based models by 21.46%and 46.40%at the maximum,respectively.The proposed framework is expected to provide an effective decision support for moving trajectory control and serve as a foundation for the application of deep learning in the automatic control of pipe jacking.

关键词： dynamic prediction moving trajectory pipe jacking GRU deep learning

Haploinsufficiency of syncoilin leads to hypertrophic cardiomyopathy

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Genes & Diseases 2022年第6期9卷 1412-1414页

作者： Liang-Liang Fan Zhuang-Zhuang Yuan Zi-Jun Jiao Hui Zeng yi-feng yang Zhi-Ping Tan Clinical Center for Gene Diagnosis and Therapy Department of Cardiovascular SurgeryThe Second Xiangya Hospital of Central South UniversityChangshaHunan 410011PR China Department of Cell Biology The School of Life SciencesCentral South UniversityChangshaHunan 410013PR China Hunan Key Laboratory of Animal for Human Disease School of Life SciencesCentral South UniversityChangshaHunan 410013PR China

Here we reported a SYNC nonsense variant in a Chinese family with hypertrophic cardiomyopathy(HCM)and firstly linked syncoilin(SYNC)to HCM.HCM is an inherited cardiovascular disease,affecting approximately 1:500 people,that is characterized by thickening of left ventricle(LV),especially the interventricular septum(IVS),and diastolic ventricular failure.1 To date,more than 15 genes of two groups underlying HCM have been identified.1 About 35%e60%HCM patients present autosomal dominant inheritance and carry a pathogenic variant in sarcomeric protein genes,such as b-myosin heavy chain(MYH7),myosin binding protein C(MYBPC3),and Troponin T(TNNT2).1 In addition,non-sarcomeric genetic causes of disease have also been observed in about 25%HCM patients,mainly related to metabolic storage diseases,mitochondrial cardiomyopathies,inborn errors of metabolism etc.

关键词： metabolism cardiomyopathy ventricular

Heavy fermion quantum criticality: The party is just beginning

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Science China(Physics,Mechanics & Astronomy) 2020年第11期63卷 129-130页

作者： yi-feng yang Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China

Recently,Nature reported the discovery of a ferromagnetic quantum critical point(FM QCP)in the heavy fermion compound CeRh6Ge4[1].This is the first discovery of such kind in a stoichiometric compound.The FM order is suppressed at a critical pressure of 0.8 GPa,beyond which the ground state turns into a Fermi liquid.Previously,Science had also reported the observation of a FM QCP,albeit in the doped compound YbNi4(P0.92As0.08)2[2].

关键词： compound. quantum compound

Observation of Mott instability at the valence transition of f-electron system

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National Science Review 2023年第6期10卷 183-190页

作者： Haifeng yang Jingjing Gao yingying Cao Yuanji Xu Aiji Liang Xiang Xu Yujie Chen Shuai Liu Kui Huang Lixuan Xu Chengwei Wang Shengtao Cui Meixiao Wang Lexian yang Xuan Luo Yuping Sun yi-feng yang Zhongkai Liu Yulin Chen Collaborative Innovation Center of Microstructures Nanjing University Songshan Lake Materials Laboratory Department of Physics University of Oxford School of Physical Science and Technology Shanghai Tech University Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Sciences Science Island Branch of Graduate School University of Science and Technology of China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Shanghai Tech Laboratory for Topological Physics State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics Tsinghua University State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology (SIMIT) Chinese Academy of Sciences High Magnetic Field Laboratory Chinese Academy of Sciences

Mott physics plays a critical role in materials with strong ele ctronic correlations.Mott insulator-to-metal transition can be driven by chemical doping,external pressure,temperature and gate voltage,which is often seen in transition metal oxides with 3d electrons near the Fermi energy(e.***.cuprate superconductor).In4f-electron systems,however,the insulator-to-metal transition is mostly driven by Kondo hybridization and the Mott physics has rarely been explored in experiments.Here,by combining the angle-resolved photo emission spectroscopy and strongly correlated band structure calculations,we show that an unusual Mott instability exists in YbInCu4accompanying its mysterious first-order valence transition.This contrasts with the prevalent Kondo picture and demonstrates that YbInCu4is a unique platform to explore the Mott physics in Kondo lattice systems.Our work provides important insight for the understanding and manipulation of correlated quantum phenomena in the f-electron system.

关键词： valence transition orbital-selectiveMott transition Kondo coupling heavy fermions strong correlations ARPES DMFT

Impurity-induced bound states as a signature of pairing symmetry in multiband superconducting CeCu2Si2

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Frontiers of physics 2019年第1期14卷 99-104页

作者： Dong-Dong Wang Bin Liu Min Liu yi-feng yang Shi-Ping feng Department of Physics Beijing Jiaotong University Beijing 100044 China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China Collaborative Innovation Center of Quantum Matter Beijing 100190 China Department of Physics Beijing Normal University Beijing 100875 China

The notion of multiband superconductivity with dominant two-gap features has been recently applied to the unconventional superconductor CeCu2Si2 for challenging the previously accepted concept of nodal d-wave pairing. In the proposed study, the realistic multiband Fermi surface topology of CeCu2Si2 was obtained through first-principles calculations, and analysis was conducted with an effective two-band hybridization model including detailed band structure. Within the T-matrix approximation, the obtained calculation results show that different pairing candidates, including fully gapped s-wave, loop-nodal s-wave, and d-wave pairings, could yield qualitatively distinct features characterized by impurity-induced bound states. These features can be verified through high-resolution scanning tunneling microscopy or spectroscopy and provide corroborative justification that would be beneficial for the ongoing research regarding the superconducting gap symmetry of CeCu2Si2 at ambient pressure.

关键词： heavy-fermion superconductivity pairing symmetry impurity effect local density of states

Hybridization-mediated quasiparticle and phonon dynamics in single crystal cerium films

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Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 146-153页

作者： Yunhe Pei yi Wu Kai Hu Zhengxing Wei yifeng yang yang Liu Jingbo Qi State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 611731China Center for Correlated Matter and Department of Physics Zhejiang UniversityHangzhou 310058China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

We report the ultrafast optical pump-probe spectroscopy measurements on the single-crystal cerium films.Our experimental results of temperature-dependent quasiparticle dynamics reveal development of the hybridization between localized f moments and conduction electrons,i.e.,evolving from fluctuating hybridization to collective hybridization.Exotic phonon renormalization is discovered to appear at the emerging temperature(T^(+))of fluctuating hybridization apart from its known presence at the coherent temperature(T^(*)),and can hardly be explained by the mean-field theory.The quasiparticle relaxation at high temperatures indicates coexistence of nonthermal electron-electron scattering and inelastic Kondo scattering,while its behavior at low temperatures suggests onset ofαphase in theγ-phase dominated film.We also extract the indirect gap below T^(*),representing the appearance of collective hybridization.Our findings provide novel information about the hybridization and phase evolution in the heavy fermion systems.

关键词： cerium quasiparticle dynamics hybridization phonon renormalization

Mutant CARD10 in a family with progressive immunodeficiency and autoimmunity

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Cellular & Molecular Immunology 2020年第7期17卷 782-784页

作者： Dan-hui yang Ting Guo Zhuang-zhuang Yuan Cheng Lei Shui-zi Ding yi-feng yang Zhi-ping Tan Hong Luo Department of Respiratory Medicine The Second Xiangya HospitalCentral South UniversityChangshaHunan 410011China Research Unit of Respiratory Disease Central South UniversityChangshaHunan 410011China Hunan Diagnosis and Treatment Center of Respiratory Disease ChangshaHunan 410011China School of Life Sciences Central South UniversityChangshaHunan 410013China Clinical Center for Gene Diagnosis and Therapy Department of Cardiovascular SurgeryThe Second Xiangya Hospital of Central South UniversityChangshaHunan 410011China

Autoimmunity and immunodeficiency were previously considered to be mutually exclusive conditions.However,an increased understanding of the complex immune regulatory systems and signaling mechanisms,coupled with the application of genetic analysis,has demonstrated the complex relationships between the two kinds of diseases.1 In recent years,several mild forms of primary immunodeficiencies have been discovered,presenting with opportunistic infections overlapping autoimmunity and/or allergy late in life.

关键词： conditions. mutually mild