3 research outputs found
Strong interlayer coupling in monoclinic GaTe
Recently, emerging intriguing physical properties have been unraveled in
anisotropic layered semiconductors, with their in-plane anisotropy often
originated directly from the low crystallographic symmetry. However, little has
been known in the case where interlayer couplings dominate the anisotropy of
electronic band structures in them. Here, by both experiment and theory, we
show rather than geometric factors, the anisotropic energy bands of monoclinic
gallium telluride (GaTe) are determined by a subtle bulk-surface interaction.
Bulk electronic states are found to be the major contribution of the highest
valence band, whose anisotropy is yet immune to surface doping of potassium
atoms. The above peculiar behaviors are attributed to strong interlayer
couplings, which gives rise to an inverse of anisotropy of hole effective
masses and a direct-indirect-direct transition of band gap, depending on the
number of layers. Our results thus pave the way for future applications of
anisotropic layered semiconductors in nanoelectronics and optoelectronics.Comment: 3 figure
Quasi-Two-Dimensional Fermi Surface and Heavy Quasiparticles in CeRh2As2
The recent discovery of multiple superconducting phases in CeRh2As2 has
attracted considerable interest. These rich phases are thought to be related to
the locally noncentrosymmetric crystal structure, although the possible role of
a quadrupole density wave preceding the superconductivity remains an open
question. While measurements of physical properties imply that the Ce 4f
electrons could play an essential role, the momentum-resolved electronic
structure remains hitherto unreported, hindering an in-depth understanding of
the underlying physics. Here, we report a high-resolution angle-resolved
photoemission study of CeRh2As2. Our results reveal fine splittings of
conduction bands, which are directly related to the locally noncentrosymmetric
structure, as well as a quasi-two-dimensional Fermi surface, implying weak
interlayer hopping and possible nesting instabilities. Our experiments also
uncover the fine structures and pronounced temperature evolution of the Kondo
peak, demonstrating strong Kondo effect facilitated by excited crystal electric
field states. Our results unveil the salient electronic features arising from
the interplay between the crystal structure and strong electron correlation,
providing spectroscopic insight for understanding the heavy fermion physics and
unconventional quadrupole density wave in this enigmatic compound