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Updated: Aug 16, 2025
Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
Extremely Shallow Valence Band in Lanthanum Trihydride
Tomoyuki Yamasaki1, Soshi Iimura1,2,3, Junghwan Kim1,3
1International Research Frontiers Initiative MDX Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan.
Abstract:
Hydride ions (H-) in solvents are chemically active anions with strong electron-donating ability and are used as reducing agents in organic chemistry. Here, we evaluate the energy level of 1s-electrons in H- accommodated in solid lanthanum hydrides, LaH (2 ≤ x ≤ 3), by photoemission (ultraviolet photoelectron and photoelectron yield spectroscopies) measurements and density functional theory calculations. We show that a very shallow valance band maximum with an ionization potential of 3.8 eV is attained in LaH3 and that the primary cause is attributed to the small electronegativity of hydrogen and the significant bonding-antibonding interaction between neighboring H-s with a close separation originating from the H-stuffed fluorite-related structure. These results encourage the challenge for p-type conduction in hydride semiconductors and provide a clue to the chemical understanding of polyhydride superconductors.
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