2005 APCTP Summer School on Strongly Correlated Electron SystemsAsia Pacific Center for Theoretical Physics & POSTECH, Pohang, Korea

Photoemission spectroscopy of Photoemission spectroscopy of transitiontransition--metal oxides, metal oxides,

highhigh--temperature superconductors, temperature superconductors, and magnetic semiconductorsand magnetic semiconductors

Atsushi FUJIMORI University of Tokyo

Phase diagram of a correlated electron systemPhase diagram of a correlated electron system

1 electron/atomT = 0 K

SpinSpin--chargecharge--orbital coupling andorbital coupling andGiant response of correlated electron systemsGiant response of correlated electron systems

Correlated electron systems/Correlated electron systems/Complex materials Complex materials

La2-xSrxCuO4

Ga1-xMnxAs

Photoemission spectroscopyPhotoemission spectroscopy

AngleAngle--Resolved Photoemission SpectroscopyResolved Photoemission SpectroscopyARPESARPES

EF

AngleAngle--Resolved Photoemission SpectroscopyResolved Photoemission SpectroscopyARPESARPES

AngleAngle--Resolved Photoemission SpectroscopyResolved Photoemission SpectroscopyARPESARPES

kx

ky Fermi sruface

EF

below EF

k

Band dispersion

Fermi surfaces of strongly correlated systemFermi surfaces of strongly correlated system

A. Damascelli, et al., PRL ‘00

Fermi surface of Sr2RuO4from ARPES

Fermi surface of Sr2RuO4 from de Haas-van Alfven effect

C. Bergemann et al., Phys. Rev. Lett. ‘00

Synchrotron radiationSynchrotron radiation

electron

acceleration

velocitySR

Characteristics

• tunable energy

• fixed/variable polarization

• high intensity

• low emittance

electron

SR from bend magnet

electron

SR from undulatorSpring-8 Home Page

Synchrotron radiationSynchrotron radiation

Characteristics

• tunable energy

• fixed/variable polarization

• high intensity

• low emittance

electron

acceleration

velocitySR

electron

electron

SR from bend magnet

SR from undulator

放射光の特徴

・波長連続可変

・偏光性

・大強度

・指向性

SR from bend magnet

sun light

medical x-ray

rotating anode

wiggler

soft x-ray udulator

Spring-8 undulatorlong undulator

Photon energy (eV)

Wave length (nm)

VIS VUV X

IR UV SX

Brilli

ance

(pho

tons

/sec

/mm

2/m

drad

2 0.

1% b

and

pass

)

Spring-8 Home Page

Synchrotron radiation facilitiesSynchrotron radiation facilities

OutlineOutline

• Transition-metal oxides– Mott insulators– Metal-insulator transitions

• High-temperature superconductors• Magnetic semiconductors

General references: M. Imada, A. Fujimori, and Y. Tokura: Metal-Insulator Transitions, Rev. Mod. Phys. 70 (1998)

1039.N. Tsuda, K. Nasu, A. Fujimori and K. Siratori: Electronic Conduction in Oxides (Springer-

Verlag, Berlin, 2000).T. Mizokawa, A. Fujimori, J. Okabayashi and O. Rader: Photoemission Spectroscopy of Diluted Mn in and on Solids, J. Electron Spectrosc. Relat. Phenom. 136 (2004) 21.