Chern mosaic: Topology of chiral superconductivity on ferromagnetic adatom lattices

Abstract

In this work we will explore the properties of superconducting surfaces decorated by twodimensional ferromagnetic adatom lattices. As discovered recently [Röntynen and Ojanen, Phys. Rev. Lett. 114, 236803 (2015)], in the presence of a Rashba spin-orbit coupling these systems may support topological superconductivity with complex phase diagrams and high Chern numbers. We show how the long-range hopping nature of the effective low-energy theory generically gives rise to a phase diagram covered by a Chern mosaic -a rich pattern of topological phases with large Chern numbers. We study different lattice geometries and the dependence of energy gaps and abundance of different phases as a function of system parameters. Our findings establish the studied system as one of the richests platforms for topological matter known to date.

Ground-state angular momentum, spectral asymmetry, and topology in chiral superfluids and superconductors

“…These systems do not exhaust the list of chiral superfluids; in addition to the intrinsic chiral superconductors and superfluids, there exist various schemes to engineer chiral superconductors by combining simple systems into heterostructures [22]. For example, recently it was discovered that superconductors with high Chern numbers could be realized in planar systems with magnetic adatoms [23,24]. Also, a recent proposal suggests that Sr 2 RuO 4 would actually be described by a Chern number 7 state [25].…”

Topological state engineering by potential impurities on chiral superconductors

“…Superstructures fabricated from magnetic atoms are currently under active experimental [15][16][17] and theoretical research [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Intriguing properties of these systems include the possibility for various one-dimensional (1D) topological superconducting phases with Majorana bound states and rich two-dimensional (2D) topological phases [34][35][36][37]. A topologically nontrivial phase is known to arise in 1D ferromagnetic arrays when the underlying superconductor has a strong Rasha spin-orbit coupling or in arrays with helical magnetic textures.…”

Bound States Induced by the Ferromagnetic Dimer in a Triangular Lattice

“…[14] for a review). The pursuit to obtain stable, topologically non-trivial phases has extended from one-dimensional to two-dimensional lattices of the magnetic impurities [15][16][17][18][19][20][21][22], however to fully understand the phenomena in those rich systems, it is useful to study a simpler system, i.e. a dimer of impurities embedded in a superconductor.…”