Orbital nematic instability in the two-orbital Hubbard model: renormalization-group + constrained RPA analysis.

Motivated by the nematic electronic fluid phase in Sr(3)Ru(2)O(7), we develop a combined scheme of the renormalization-group method and the random-phase-approximation-type method, and analyze orbital susceptibilities of the (d(xz), d(yz))-orbital Hubbard model with high accuracy. It is confirmed that the present model exhibits a ferro-orbital instability near the magnetic or superconducting quantum criticality, due to the Aslamazov-Larkin-type vertex corrections. This mechanism of orbital nematic order presents a natural explanation for the nematic order in Sr(3)Ru(2)O(7), and is expected to be realized in various multiorbital systems, such as Fe-based superconductors.