Angle‐Resolved Photoemission of Topological Matter: Examples from Magnetism, Electron Correlation, and Phase Transitions

AbstractUnusual phase transitions driven by electron correlation effects occur in many f-electron metals (lanthanides and actinides alike) from localized phases to itinerant phases at high pressures. The dramatic changes in atomic volumes and crystal structures associated with some of these transitions signify equally important changes in the underlying electronic structure of these correlated f-electron metals. Yet, the relationships among the crystal structure, electronic correlation and electronic structure in f-electron metals have not been well understood. In this study, utilizing recent advances in third-generation synchrotron x-ray spectroscopies and high-pressure diamond-anvil cell technologies, we describe the pressure-induced spectral changes across the volume collapse transition in Gd at 60 GPa and well above. The spectral results suggest that the f-electrons of high-pressure Gd phases are highly correlated even at 100 GPa – consistent with the Kondo volume collapse model and the recent experimental evidence of strong electron correlation of α-Ce.

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Electron correlation influenced magnetic phase transitions in f-electron systems

Physica B+C ◽

10.1016/0378-4363(80)90145-x ◽

1980 ◽

Vol 102 (1-3) ◽

pp. 145-147

Author(s):

Th. Frauenheim ◽

G. Ropke

Keyword(s):

Phase Transitions ◽

Electron Correlation ◽

Magnetic Phase ◽

Magnetic Phase Transitions ◽

Electron Systems

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INFLUENCE OF ELECTRON-ELECTRON CORRELATION ON THE JAHN-TELLER-TYPE STRUCTURAL PHASE TRANSITIONS

Acta Physica Sinica ◽

10.7498/aps.40.1474 ◽

1991 ◽

Vol 40 (9) ◽

pp. 1474

Author(s):

WU JIAN-BI

Keyword(s):

Phase Transitions ◽

Electron Correlation ◽

Structural Phase ◽

Structural Phase Transitions ◽

Jahn Teller

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Electron Microscopy of Graphite Intercalation Compounds

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055564 ◽

1982 ◽

Vol 40 ◽

pp. 544-545

Author(s):

G. Timp ◽

L. Salamanca-Riba ◽

L.W. Hobbs ◽

G. Dresselhaus ◽

M.S. Dresselhaus

Keyword(s):

Electron Microscopy ◽

Phase Transitions ◽

Domain Wall ◽

Intercalation Compounds ◽

Lattice Plane ◽

Wall Model ◽

Graphite Intercalation Compounds ◽

Fundamental Symmetry ◽

Graphite Intercalation

Electron microscopy can be used to study structures and phase transitions occurring in graphite intercalations compounds. The fundamental symmetry in graphite intercalation compounds is the staging periodicity whereby each intercalate layer is separated by n graphite layers, n denoting the stage index. The currently accepted model for intercalation proposed by Herold and Daumas assumes that the sample contains equal amounts of intercalant between any two graphite layers and staged regions are confined to domains. Specifically, in a stage 2 compound, the Herold-Daumas domain wall model predicts a pleated lattice plane structure.

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To What Extent are Inelastically Scattered Electrons Useful in the Stem?

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071879 ◽

1973 ◽

Vol 31 ◽

pp. 286-287 ◽

Cited By ~ 2

Author(s):

H. Rose

Keyword(s):

Electron Microscope ◽

High Resolution ◽

Electron Correlation ◽

Quantum Noise ◽

Collection Efficiency ◽

Scanning Transmission Electron Microscope ◽

Electron Cloud ◽

Scanning Time ◽

Transmission Electron ◽

Scanning Transmission

The scanning transmission electron microscope offers the possibility of utilizing inelastically scattered electrons. Use of these electrons in addition to the elastically scattered electrons should reduce the scanning time (dose) Which is necessary to keep the quantum noise below a certain level. Hence it should lower the radiation damage. For high resolution, Where the collection efficiency of elastically scattered electrons is small, the use of Inelastically scattered electrons should become more and more favorable because they can all be detected by means of a spectrometer. Unfortunately, the Inelastic scattering Is a non-localized interaction due to the electron-electron correlation, occurring predominantly at the circumference of the atomic electron cloud.

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Multiple phase transitions investigated by high-speed TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100175880 ◽

1990 ◽

Vol 48 (4) ◽

pp. 550-551

Author(s):

Oleg Bostanjoglo ◽

Peter Thomsen-Schmidt

Keyword(s):

Phase Transitions ◽

High Speed ◽

Short Exposure ◽

Semiconductor Film ◽

Time Resolved ◽

Short Exposure Time ◽

Multiple Phase ◽

Model Substance ◽

History Of ◽

Electron Image

Thin GexTe1-x (x = 0.15-0.8) were studied as a model substance of a composite semiconductor film, in addition being of interest for optical storage material. Two complementary modes of time-resolved TEM were used to trace the phase transitions, induced by an attached Q-switched (50 ns FWHM) and frequency doubled (532 nm) Nd:YAG laser. The laser radiation was focused onto the specimen within the TEM to a 20 μm spot (FWHM). Discrete intermediate states were visualized by short-exposure time doubleframe imaging /1,2/. The full history of a transformation was gained by tracking the electron image intensity with photomultiplier and storage oscilloscopes (space/time resolution 100 nm/3 ns) /3/. In order to avoid radiation damage by the probing electron beam to detector and specimen, the beam is pulsed in this continuous mode of time-resolved TEM,too.Short events ( <2 μs) are followed by illuminating with an extended single electron pulse (fig. 1c)

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