Electronic Structure of Mott Insulators Studied by Inelastic X-ray Scattering

Hasan, M. Z.
Isaacs, E. D.
Shen, Z.-X.
Miller, L. L.
Tsutsui, K.
Tohyama, T.
Maekawa, S.

¹Department of Applied Physics, Stanford Synchrotron Radiation Laboratory (SSRL), and Stanford Linear Accelerator Center (SLAC), Stanford University, Stanford, CA 94305, USA. ²Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA. ³Department of Physics and Ames Laboratory, Iowa State University, Ames, IA 50011, USA. ⁴Institute of Materials Research, Tohoku University, Sendai 980-8577, Japan.

*To whom correspondence should be addressed. E-mail: [email protected]

9 February 2000; accepted 20 April 2000

Science 288(5472):p 1811-1814, June 9, 2000.

The electronic structure of Mott insulators continues to be a major unsolved problem in physics despite more than 50 years of research. Well-developed momentum-resolved spectroscopies such as photoemission or neutron scattering cannot probe the full Mott gap. High-resolution resonant inelastic x-ray scattering revealed dispersive charge excitations across the Mott gap in a high-critical temperature parent cuprate (Ca₂CuO₂Cl₂), shedding light on the anisotropy of the Mott gap. These charge excitations across the Mott gap can be described within the framework of the Hubbard model.