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Robust Spin Crossover and Memristance across a Single Molecule

Toshio Miyamachi*, Manuel Gruber, Vincent Davesne, Martin Bowen, Samy Boukari, Loïc

Joly, Fabrice Scheurer, Guillaume Rogez, Toyo Kazu Yamada, Philippe Ohresser, Eric

Beaurepaire, and Wulf Wulfhekel

*Correspondence to T. M. (toshio.miyamachi@kit.edu)

Supplementary Figures S1-S4

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Supplementary Figures

Supplementary Figure S1, STM images of 2 monolayers of Fe-phen on Cu(100).

(a) Large-scale and (b) zoomed STM image of 2 ML Fe(phen)2(NCS) 2 thin film on Cu(100)

obtained at 4.6 K. Scanning parameters are 160 pA and + 0.6 V. The red and blue dotted boxes in

(b) denote Fe-phen molecules in the HS and LS states similar to single molecules adsorbed on

Cu(100).

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Supplementary Figure S2, Frozen spin states of individual Fe-phen molecules on Cu(100).

(a) An STM image of individual Fe-phen HS and LS molecules on Cu(100). (b) Height profiles of

HS and LS molecules in (a). (c) Bias dependencies of the STM height profile for the HS state

(upper panel) and the LS state (lower panel). No switching of the states was observed. (d)

I(V)-curves recorded atop the center of an individual molecule adsorbed onto Cu(100) in the bias

range -1.8V to 1.8V reveal no hysteretic switching behaviour.

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Supplementary Figure S3, Growth of whole CuN layer on Cu(100) surface.

(a) Large scale STM image of Cu(100) surface covered with a continuous CuN layer. (b)

Atomic resolution of the CuN/Cu(100) surface showing a c(2x2) reconstruction on the islands

and the trenches between the islands in agreement with previous results [30]. (c) An STM image

of Fe-phen single molecules on the CuN/Cu(100) surface. The molecule encircled by red (blue)

is in the HS (LS) state. Difference between HS and LS states is noticeable at the central regions

of the molecule as mentioned in the main manuscript. (d) A differentiated STM image with an

enhanced contrast of the CuN/Cu(100) surface with a Fe-phen single molecule. Atomic

resolution of CuN layer is clearly recognizable.

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Supplementary Figure S4, Molecular states of individual Fe-phen molecules on

CuN/Cu(100).

dI/dV spectra recorded on (a) the center and (b) the ligand of the HS and the LS states on

CuN/Cu(100) and Cu(100) surfaces. The spectra recorded on the ligands of the HS and LS state

of the molecules on CuN/Cu(100) differ significantly in case they are adsorbed on

CuN/Cu(100) in agreement with expected electronic differences of the HS and LS state [31].

The spectra of the molecules on bare Cu(100) show only minor signals due to the strong

hybridization with the substrate. The spectra were acquired with a modulation bias of 10 mV

and a frequency of 723 Hz.

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Supplementary References

[32] Leibsle, F. M. et al. Structure of the Cu{100}-c(2×2)N surface: A

scanning-tunneling-microscopy study. Phys. Rev. B. 47, 15865-15868 (1993).

[33] Reiher, M. Theoretical Study of the Fe(phen)2(NCS)2 Spin-Crossover Complex with

Reparametrized Density Functionals. Inorg, Chem. 41, 6928-6935 (2002).