Magnetic and electronic structure of Mn nanostructures on Ag(111) and Au(111)

We show for a simple non-collinear configuration of the atomistic spins (in particular, where one spin is rotated by a finite angle in a ferromagnetic background) that the pairwise energy variation computed in terms of multiple scattering formalism cannot be fully mapped onto a bilinear Heisenberg spin model even in the lack of spin-orbit coupling. The non-Heisenberg terms induced by the spin-polarized host appear in leading orders in the expansion of the infinitesimal angle variations. However, an Eg-T2g symmetry analysis based on the orbital decomposition of the exchange parameters in bcc Fe leads to the conclusion that the nearest neighbor exchange parameters related to the T2g orbitals are essentially Heisenberg-like: they do not depend on the spin configuration, and can in this case be mapped onto a Heisenberg spin model even in extreme non-collinear cases.

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“…[33], in some cases as for the second neighbor pairs the decomposition is complete, however, in general we have a finite mixed term, A αβ−mix i…”

Section: Resultsmentioning

confidence: 99%

Theory of noncollinear interactions beyond Heisenberg exchange: Applications to bcc Fe

et al. 2017

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“…A fully real-space calculation of the interactions in a magnetic cluster is presented in Ref. [15]. However, only considering two-spin interactions in the spin model is not sufficient for describing all types of magnetic order.…”

Section: Introductionmentioning

confidence: 99%

Magnetic structure of monatomic Fe chains on Re(0001): Emergence of chiral multispin interactions

et al. 2019

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We present results of first-principles calculations of the magnetic properties of Fe chains deposited on the Re(0001) surface. By increasing the length of the chain, a transition is found from an almost collinear antiferromagnetic state for a five-atom-long chain to a spin spiral state with the rotational plane slightly tilted from the surface of the substrate for the 15-atom-long chain. It is shown that a classical spin model derived from the ab initio calculations containing only two-spin interactions supports opposite chirality of the spin spiral compared to a direct optimization of the spin configuration within the ab initio method. The differences between the results of the two methods can be understood by introducing chiral four-spin interactions in the spin model.

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“…Thereby, these atoms tend to have a different bonding length and, thus, a different hybridization with the substrate as compared to those in the interior of the chain. Moreover, the spin-related properties at the ends of magnetic chains can differ drastically from their interior [18][19][20] . All this could lead to a localization of topologically trivial Yu-Shiba-Rusinov (YSR) states at the chain's ends 9,13,17,21,22 and also accidentally close to the Fermi energy, and, therefore, hinder the identification of the spectral weight stemming from the sought-after Majorana bound states.…”

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confidence: 99%

Controlling in-gap end states by linking nonmagnetic atoms and artificially-constructed spin chains on superconductors

et al. 2020

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Chains of magnetic atoms with either strong spin-orbit coupling or spiral magnetic order which are proximity-coupled to superconducting substrates can host topologically non-trivial Majorana bound states. The experimental signature of these states consists of spectral weight at the Fermi energy which is spatially localized near the ends of the chain. However, topologically trivial Yu-Shiba-Rusinov in-gap states localized near the ends of the chain can lead to similar spectra. Here, we explore a protocol to disentangle these contributions by artificially augmenting a candidate Majorana spin chain with orbitally-compatible nonmagnetic atoms. Combining scanning tunneling spectroscopy with ab-initio and tight-binding calculations, we realize a sharp spatial transition between the proximity-coupled spiral magnetic order and the non-magnetic superconducting wire termination, with persistent zero-energy spectral weight localized at either end of the magnetic spiral. Our findings open a new path towards the control of the spatial position of in-gap end states, trivial or Majorana, via different chain terminations, and the realization of designer Majorana chain networks for demonstrating topological quantum computation.

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Magnetic and electronic structure of Mn nanostructures on Ag(111) and Au(111)

Cited by 25 publications

References 42 publications

Theory of noncollinear interactions beyond Heisenberg exchange: Applications to bcc Fe

Theory of noncollinear interactions beyond Heisenberg exchange: Applications to bcc Fe

Magnetic structure of monatomic Fe chains on Re(0001): Emergence of chiral multispin interactions

Controlling in-gap end states by linking nonmagnetic atoms and artificially-constructed spin chains on superconductors

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