Quasiparticle scattering image in hidden order phases and chiral superconductors

Momentum-resolved superconducting energy gaps of Sr 2 RuO 4 from quasiparticle interference imaging

“…Theories of Sr2RuO4 BQPI demonstrate how these q-vectors encode the direction of the gap minima in Δ ( ); Δ ( ), and also predict a very weak dispersion of the subgap ( , ) with energy 39,40,41 . The observed pattern of ( , = 100 ) maxima in ±0.1 rad away from the (0,0) → (±1, ±1) / lines 18,19,28,31 ; or if the energy resolution is insufficient to resolve them, they should exhibit as a broad arc connecting these ( , 0) maxima.…”

“…Thus, techniques capable of band-resolved, high resolution superconducting Δ( ) determination, and specifically of distinguishing the orientation of any gap minima on different bands, are required. Bogoliubov quasiparticle interference imaging [32][33][34][35][36][37][38] has been proposed 39,40,41 to achieve these objectives for Sr2RuO4, as it has the proven capability of measuring extremely anisotropic [33][34][35][36][37][38] , multiband 35,36,38 superconducting energy gaps with energy resolution 36,38 ≲ 75 . Intuitively, this is possible because, when a highly anisotropic Δ opens on a given band, Bogoliubov quasiparticles | ( )⟩ exist in the energy range Δ <E<Δ .…”

“…1d represents a BQPI model with anisotropic energy gaps Δ ( ); Δ ( ) on the α:β-bands. The experimental challenge is to visualize Bogoliubov scattering interference in Sr2RuO4 and, through comparison with δ ( , ) predictions 39,40,41 , to determine Δ ( ) .…”