2026/07/20 by Ya-Hui Zhang · 1 citation
#cond-mat.str-el #cond-mat.supr-con
We develop a unified framework for metallic and superconducting phases obtained by doping a fractional Chern insulator (FCI) with C=1/3. Starting from the parton construction c(\mathbf r)=f1(\mathbf r)f2(\mathbf r)f3(\mathbf r), the low-energy theory has SU(3)gauge× SU(3)valley symmetry and nine Fermi pockets formed by charge--e/3 holons ψab, where a and b label color and valley. Viewing the holons as quarks connects this problem to color superconductivity in high-energy physics. Color-antisymmetric pairing produces a class of charge-2e superconductors with angular momentum L=3n and chiral central charge c-=m/2, where m is odd. Thus a gas of charge-e/3 anyons can enter a superconducting phase directly without binding. Particle--hole color--valley Higgs fields instead produce two Z3 orthogonal metals with one or three pockets, transforming respectively as a singlet or triplet of SU(3)valley. A U(1)2 holon metal with three identical pockets can preserve the triangular-lattice space group while reducing the emergent valley symmetry down to S3. Its pairing instabilities include a gapped charge 2e f-if superconductor and a gapless charge-2e orthogonal superconductor with ⟨ cc⟩=0 and a Bogoliubov Fermi surface at Γ. Finally, we discuss the possibility of a chemical-potential-tuned transition from the FCI to superconductivity and argue that all nine fermions may be required if the transition preserves the full emergent SU(3)v symmetry.