Fermion-fermion interaction driven phase transitions in the rhombohedral trilayer graphene

The effects of short-range fermion-fermion interactions on the low-energy properties of the rhombohedral trilayer graphene are comprehensively investigated by virtue of the momentum-shell renormalization group method. We take into account all one-loop corrections and establish the energy-dependent coupled evolutions of independent fermionic couplings that carry the physical information stemming from the interplay of various fermion-fermion interactions. With the help of the detailed numerical analysis, we notice that the ferocious competition among all fermion-fermion interactions can drive fermionic couplings to four distinct kinds of fixed points, dubbed FP₁, FP₂, FP₃ and FP₄, in the interaction-parameter space. Such fixed points principally dictate the fate of the system in the low-energy regime, which are always associated with some instabilities with specific symmetry breakings and thus accompanied by certain phase transitions. In order to judge the favorable states arising from the potential phase transitions, we bring out a number of fermion-bilinear source terms to characterize the underlying candidate states. By comparing their related susceptibilities, it is determined that the dominant states correspond to a spin-singlet superconductivity, a spin-triplet pair-density-wave, and a spin-triplet superconductivity for approaching the fixed points FP1,3, FP₂, and FP₄, respectively. These results would be helpful to further reveal the low-energy properties of the rhombohedral trilayer graphene and analogous materials.