  The triangular triple quantum dot is an interesting system which can
demonstrate various types of the Kondo effects, such as the one due to the
local spin S=1 moment caused by the Nagaoka ferromagnetic mechanism and the
SU(4) Kondo effect. We theoretically study the low-temperature properties and
the Kondo energy scale of the triangular triple quantum dot, using the Wilson
numerical renormalization group. We have explored a wide parameter region of
the electron-filling and distortions which break the symmetry of an equilateral
structure. Our results give a comprehensive overview of how the Kondo behavior
varies in the different the regions in the wide parameter space of the
triangular triple quantum dot.
