In the magic angle twisted bilayer graphene (TBG), one of the most remarkable observations is the $C_3$-symmetry-breaking nematic state. We identify that the nematicity in TBG is the $E$-symmetry ferro bond order, which is the symmetry breaking in the effective hopping integrals. Thanks to the strong correlation and valley degree of freedom characteristics of the TBG, the nematicity in the TBG originates from prominent quantum interference among valley fluctuations and spin fluctuations. This novel valley + spin fluctuation interference mechanism also causes novel time-reversal-symmetry-broken valley polarization accompanied by a charge loop current. We discuss interesting similarities and differences between the TBG and Fe-based superconductors.
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