Current-induced forces. current

Transcription

1 Current-induced forces current force? force 1

2 Electromigration H.B. Heersche et al., Appl. Phys. Lett. 91, (2007). 2

3 Indium atom transport over CNT TEM image CNT In nanoparticle current current current Regan, Aloni, Ritchie, Dahmen, Zettl, Nature 428, 924 (2004) 3

4 Atomic steps on Ag(111) Boncharduk et al., Phys.Rev.Lett. 99, (2007) 4

5 Current induced cleaning of graphene Moser, Barreiro, Bachtold, Appl.Phys.Lett. 91, (2007) 5

6 Basic concepts of electromigration F ez * d ez * w E Effective valence. For metals typically Direct force: associated with Landauer dipole 6

7 Towards microscopic understanding of current induced forces Theory is mostly phenomenological Experiments probing forces on atomic scale are almost absent 7

8 Current induced single-atom switching Schirm et al. Nature Nanotechnol. 8, 645 (2013) 8

9 Current-induced single switching Low tunnel current (molecule not rotating) STM of molecules adsorbed to Cu(111) 1 nm Tierney et al., Nature Nanotechn. 6, 625 (2011) See also: Perera et al., Nature Nanotechn. 8, 46 (2013) 9

10 10

11 Atomic water wheel D. Dundas, E.J. McEniry, T.N. Todorov, Nature Nanotechnol., 4, (2009). 11

12 The Berry force Lü, Brandbyge, Hedegård, Nano Lett. 10, 1657 (2010). The electron wavefunction ϕ depends on the positions of the ions R. Projecting out the electronic states, Leads to an effective magnetic field Semi-classical Langevin equation for the motion of ion cores 12

13 Model system: two degrees of freedom Lü, Brandbyge, Hedegård, Nano Lett. 10, 1657 (2010). 13

14 A model system: chain of Au atoms Lü, Brandbyge, Hedegård, Nano Lett. 10, 1657 (2010). 14

15 Experiments of current-induced breaking 15

16 Experiments of current-induced breaking Smit, Untiedt, van Ruitenbeek, Nanotechnol. 15, S472 (2004). 16

17 Experiments of current-induced breaking Smit, Untiedt, van Ruitenbeek, Nanotechnol. 15, S472 (2004). 17

18 Experiments of current-induced breaking Sabater, Untiedt, van Ruitenbeek, to be published 18

19 Experiments of current-induced breaking Initial stability test at 10mV Sabater, Untiedt, van Ruitenbeek, to be published 19

20 Pt chain: higher energy runaway mode 20

21 Pt chain: higher energy runaway mode 21

22 Can we do these experiments in a more controlled way? STM Tip Atomic Chain Molecule 22

23 Low-temperature STM Au (111) atomic resolution Electronic edge states The Beast 23

24 Deposition of single atoms by low-t evaporation Au ad-atoms over Au(111) surface 24

25 PRL 79, (1997) J. Vac. Sci. Technol., B 23(2005) Lateral manipulation of atoms STM Tip

26 Single atom manipulation: Au on Au(111) 26

27 Single atom manipulation: Au on Au(111) 27

28 Single atom manipulation: Au on Au(111) 28

29 Single atom manipulation: Au on Au(111) 29

30 Single atom manipulation: Au on Au(111) 30

31 Single atom manipulation: Au on Au(111) 31

32 Connected chain formation 32

33 Connected chain formation 33

34 Connected chain formation 34

35 Connected chain formation Three atoms chain 35

36 Single-molecule conductors 47 cycles Courtesy: Wagner C. Fournier (Tautz) et al., PRB 84, (2011) 36

37 Single-molecule conductors 37 Fournier (Tautz) et al., PRB 84, (2011)

38 STM Tip Building atomic conductors between tip and sample Atomic Chain 38

39 3-dimensional STM control x y z feedback Force field simulation 39

40 Force Field Simulation Interatomic potential 1 : Second-moment approximation (SMA) to the tight-binding Hamiltonian Initialize program Load libraries Define variables and classes Load system (Tip + surface + ad atoms) Base atoms z* (V) x* (V) 3D motion sensor x,y,z Move the Base atoms of tip y*(v) Relax system for new tip position Tunnelling current feedback Visual feedback Print the new state of the system End R Cortes Huerto (Saul) et al., PRB 88, (2013)

41 Possible process suggested by simulation 41

42 STM control: The game x y z feedback Force field simulation 42

43 Can also do break junctions x y z feedback Force field simulation 43

44 The team Christian Wagner Sumit Tewari Jacob Bakermans Federica Galli Roel Smit Carlos Untiedt Carlos Sabater Tadashi Shiota Raphael Muller Marius Trouwborst Sasha Vrbica Irene Battisi Elena Tartaglini Jan Aarts Support from Sylvestre Bonnet Tchavdar Todorov Daniel Dundas Mads Brandbyge Stefan Tautz LeidenCenterUltramicroscopy 44

45 Conclusions 45

46 46