Special Quantum Matter Seminar

Spatially modulated orders such as charge-, spin-, and pair-density waves present a plethora of intriguing physical phenomena. For modulation that is commensurate with the lattice, valuable information can be inferred by considering the symmetry group at high-symmetry
momenta at the Brillouin zone edge. Here we explore a novel perspective based on extended symmetry groups in real space, and investigate the effects of spatial modulation on the interplay of ordered phases, focusing on nonsymmorphic and body-centered systems. We highlight the example of the nonsymmorphic heavy-fermion superconductor CeRh2As2, and
show that, despite the presence of inversion symmetry, density waves with the appropriate modulation vector transform as multicomponent mixed-parity irreducible representations, which allows for counterintuitive terms in the free energy. As a consequence, a
pair-density wave order can couple linearly to odd-parity antiferromagnetism and hence induce it as an improper, or secondary order, which could explain some of the experimental observations and conundrums surrounding this compound. Finally, implications of possible
modulated charge- and pair-density waves in the body-centered orthorhombic system UTe2 will also be discussed.