Nearly-free-electron system of monolayer Na on the surface of single-crystal HfSe2

T. Eknapakul, I. Fongkaew, R. Vidyasagar, J.D. Denlinger, Lewis Bawden, S.-K Mo, Philip David King, H. Takagi, S. Limpijumnong, W. Meesvasana

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8 Citations (Scopus)


The electronic structure of a single Na monolayer on the surface of single-crystal HfSe2 is investigate dusing angle-resolved photoemission spectroscopy. We find that this system exhibits analmost perfect “nearly-free-electron” behavior with an extracted effective mass of ∼1me, in contrast to heavier masses found previously for alkali metal monolayers on other substrates. Our density functional-theory calculations indicate that this is due to the large lattice constant, causing both exchange and correlation interactions to be suppressed, and to the weak hybridization between the overlayer and the substrate. This is therefore an ideal model system for understanding the properties of two-dimensional materials.
Original languageEnglish
Article number201121(R)
Number of pages5
JournalPhysical Review. B, Condensed matter and materials physics
Issue number20
Publication statusPublished - 28 Nov 2016


  • Monolayer Na
  • Weakly-interacting two-dimensional system
  • Transition metal dichalcogenide
  • HfSe2
  • Electronic structure
  • Angle-resolved photoemission spectroscopy


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