Correlated Electrons: Missing Spectroscopies
By: Dr. Zahid Hasan
The electronic structure of Mott insulators continues to be an unsolved
problem in physics despite more than half-century of intense research
efforts. Well-developed momentum-resolved spectroscopies such as
photoemission and neutron scattering cannot fully address problems
associated with the Mott gap as angle-resolved photoemission (ARPES)
can only probe the occupied states and neutrons do not couple to the
electron's charge directly. Our recent observation of dispersive
particle-hole pair excitations across the charge gap (effective Mott gap)
in several low dimensional prototype cuprate Mott insulators
using high resolution resonant inelastic x-ray scattering suggests that
the gap is highly anisotropic and momentum dependent. In addition, the
dispersion in 1-D is anomalously large which has been interpreted as the
evidence of holons (spinless collective charge mode) in 1-D.
Resonant x-ray scattering can also provide useful insights about the
doped Mott systems as in the case of doped manganese oxides where in
addition to charge and spin, orbital degrees of freedom play a crucial
role in determining the physics of these systems.
{I'll also briefly touch upon the potential use of such x-ray scattering
in studying soft or biosystems if time permits.}
Back to the Seminar Schedule
Last modified 17-March-2003 by website owner: NCNR (attn: )
