Shiba chains of scalar impurities on unconventional superconductors

Abstract

We show that a chain of nonmagnetic impurities deposited on a fully gapped two-or threedimensional superconductor can become a topological one-dimensional superconductor with protected Majorana bound states at its end. A prerequisite is that the pairing potential of the underlying superconductor breaks the spin-rotation symmetry, as it is generically the case in systems with strong spin-orbit coupling. We illustrate this mechanism for a spinless triplet-superconductor (px + ipy) and a time-reversal symmetric Rashba superconductor with a mixture of singlet and triplet pairing. For the latter, we show that the impurity chain can be topologically nontrivial even if the underlying superconductor is topologically trivial.

Bosonic topological phases of matter: Bulk-boundary correspondence, symmetry protected topological invariants, and gauging

“…Hence gauging the dualĜ 1-form global symmetry is equivalent to un-gauging G. The symmetry is generated by the world-line of A and may be understood as anyon condensation. [64][65][66][67]…”

Supercurrent as a probe for topological superconductivity in magnetic adatom chains

“…The adatoms act as magnetic impurities for the host superconductor and give rise to Yu-Shiba-Rushinov (YSR) states which hybridize to form a band dispersing within the energy gap of the superconductor [17][18][19][20]. In suitable parameter regimes, SOC induces chiral TSC in the YSR impurity band [16,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]]. An adatom chain, therefore, mimics the physics of the onedimensional Kitaev model [36] which contains isolated MBS at the ends of the chain.…”

Topological state engineering by potential impurities on chiral superconductors

“…In 1D structures there are theoretical arguments why magnetic self-tuning could result in a nontrivial ground state [20][21][22]28,32,38], though in real systems there are a number of complications. In particular, in 2D structures the nature and tunability of magnetic textures is a delicate and largely unsolved question.Very recently it was proposed that potential impurities could be utilized to realize interesting topological states in 1D structures [39] and 2D toy models [40]. The procedure requires a non-s-wave superconductor host material with chiral or helical pairing components but circumvents the need for specific magnetic textures of adatoms.…”

“…Very recently it was proposed that potential impurities could be utilized to realize interesting topological states in 1D structures [39] and 2D toy models [40]. The procedure requires a non-s-wave superconductor host material with chiral or helical pairing components but circumvents the need for specific magnetic textures of adatoms.…”