Localized and Bandlike Valence-Electron States in Fe<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span> and Ni<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span>

E. K. Li; K. H. Johnson; D. E. Eastman; J. L. Freeouf

doi:10.1103/PhysRevLett.32.470

Localized and Bandlike Valence-Electron States in Fe $S_{2}$ and Ni $S_{2}$

E. K. Li, K. H. Johnson, D. E. Eastman, and J. L. Freeouf

Phys. Rev. Lett. 32, 470 – Published 4 March 1974

Abstract

Photoemission energy distributions for $20 <~ h ν <~ 50$ eV for semiconducting Fe $S_{2}$ (fool's gold) show a narrow, ∼1 eV wide, localized uppermost valence level, whereas the corresponding levels of semiconducting Ni $S_{2}$ are broad (∼3.5 eV) and bandlike. Self-consistent-field $X α$ cluster calculations indicate that this level in Fe $S_{2}$ is the $3 d$ -like $t_{2 g}$ state, while in Ni $S_{2}$ the uppermost level is the more bandlike $e_{g}$ state, with $t_{2 g}$ states about 2 eV lower that overlap the broad S $3 p$ -derived valence bands.

Received 22 January 1974

DOI:https://doi.org/10.1103/PhysRevLett.32.470

Authors & Affiliations

E. K. Li^* and K. H. Johnson^†

Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139

D. E. Eastman and J. L. Freeouf^‡

IBM T. J. Watson Research Center, Yorktown Heights, New York 10598

^*Submitted in partial fulfillment of the requirements for the Sc.D. degree in the Department of Electrical Engineering, Massachusetts Institute of Technology. Work supported in part by the U.S. Office of Naval Research.
^†Department of Metallurgy and Materials Science. Work supported by the National Science Foundation through the Center for Materials Science and Engineering, Massachusetts Institute of Technology.
^‡Work supported in part by National Science Foundation Grant No. GH-35823, U.S. Air Force Office of Scientific Research Grant No. F44620-70-C-0089, and U.S. Atomic Energy Commission Grant No. AT(11-1)3063.