We discussed the possibility for occurrence of MgB2-like superconductivity in cubic hexaboride KB6, from experimental and theoretical points of view. We successfully synthesized KB6 polycrystals with different K-site occupancies (84-98%). Transmission electron microscopy revealed that K-site vacancies are randomly but anisotropically distributed. Magnetization measurements showed that KB6 is a paramagnetic metal, with a small hysteresis around ∼60 K. First-principles calculations indicated that KB6 has conductive covalent network of boron like in MgB2 superconductor. We found a clear difference between the Fermi surfaces of stoichiometric and hole-doped KB6, implying a possibility for control of electronic structure for superconductivity, by introduction of K-site deficiency.
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