Poster presentation

Bottom-up Construction of Molecular Spin Chains using Atom Manipulation
Fabian Paschke¹, M. Vilas-Varela², S. Fernández², F. Albrecht¹, D. Peña² and L. Gross¹

1 IBM Research Europe – Zurich, 8803 Rueschlikon, Switzerland
2 CiQUS and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain

1D spin chains or 2D spin networks are particularly interesting not only for future spintronic applications but also to explore fundamental, albeit complex physical phenomena like many-body correlations or quantum phase transitions [1]. The generation and investigation of tailored chains and networks of various size and different subunits is thus highly desirable. This has become possible with the advent of on-surface synthesis (OSS) methods in combination with high-resolution scanning probe techniques, which allows the atomically precise synthesis and characterization of hitherto elusive molecular nanostructures [2]. However, most OSS methods rely on the catalytic activity of a metal surface, which in turn can affect essential properties of the synthesized molecule due to significant molecule-substrate interaction.

Here we use the large range of manipulation abilities provided by the tip of a scanning tunneling microscope (STM) to construct artificial molecular spin chains on an insulating layer of NaCl - molecule by molecule [3]. Brominated, nonbenzenoid truxene hydrocarbons have been chosen to serve as functional building blocks, each hosting a S=3/2 ground state in its pristine form [4]. The bottom-up synthesis route of extended chains comprises dehalogenation, lateral manipulation, intermolecular bond formation and subsequent dehydrogenation. Precursor molecules, reaction intermediates and resulting spin chain nanostructures are identified by means of high-resolution atomic force microscopy (AFM). Orbital density mapping of the frontier molecular states serve as starting point to determine the spin ground state by comparison to first-principle calculations.

[1] D.-J. Choi et al., Rev. Mod. Phys. 91, 041001 (2019)
[2] S. Clair et al., Chem. Rev. 119, 4717 (2019)
[3] Q. Zhong et al., Nat. Chem. 13, 1133 (2021)
[4] S. Mishra et al., ACS Nano 16, 3264 (2022)