Atomic manipulation of in-gap states in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi><mml:mo>−</mml:mo><mml:msub><mml:mrow><mml:mi>Bi</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:mi>Pd</mml:mi></mml:math>superconductor
Cristina Mier, Jiyoon Hwang, Jin‐Kyung Kim, Yujeong Bae, Fuyuki Nabeshima, Yoshinori Imai, Atsutaka Maeda, Nicolás Lorente, Andreas J. Heinrich, Deung-Jang Choi
Abstract
Electronic states in the gap of a superconductor inherit intriguing many-body properties from the superconductor. Here, we create these in-gap states by manipulating Cr atomic chains on the $\ensuremath{\beta}\ensuremath{-}\mathrm{Bi}{}_{2}\mathrm{Pd}$ superconductor. We find that the topological properties of the in-gap states can greatly vary depending on the crafted spin chain. These systems make an ideal platform for nontrivial topological phases because of the large atom-superconductor interactions and the existence of a large Rashba coupling at the Bi-terminated surface. We study two spin chains, one with atoms two lattice parameters apart and one with $\sqrt{2}$ lattice parameters. Of these, only the second one is in a topologically nontrivial phase, in agreement with the spin interactions for this geometry.