1. G. Palasantzas, W. Broer, B. J. Kooi, J. Knoester Zernike Institute for Advanced Materials, University of Groningen, The Netherlands V. B. Svetovoy MESA+ Institute for Nanotechnology, University of Twente, The Netherlands M. Wuttig I. Physikalisches Institut (IA) and JARA-FIT, RWTH Aachen University, Germany

2. 60 groups 11 countries

3. Boesel et al., Advanced Materials 2010

4. Stanford researchers with the Stickybot If all 6.5 million setae of one gecko toes attached simultaneously  it lifts 30-40 kg ….am I a “”Drude”gecko or.… a “plasma”….one…

5. A photo showing a stainless steel adapter of 473 g hanging on a SiO2/Si-wafer supported vertically aligned SWCNT dry adhesive film (4mm x 4mm) http://www.nanowerk.com/spotlight/ Geim et al., Nature Materials 2003 Kwak et al, Advanced Materials 2011

7. Stiction & Levitation Quantum engine cycle between two Casimir force states – tap energy from vacuum (F. Pinto PRB 1999)

9. Intersting idea but…..no clear force contrast !

10. Chen et al, Opt. Express 2007, PRB 2007

11. Chang et al., PRL 2011, PRB 2012

12.  glass-like amorphous state  A laser beam heats the PCM above the melting temperature & Rapid quenching  glass-like amorphous state amorphous state  more stable crystalline phase  heating the amorphous phase with moderate intensity laser beam: amorphous state  more stable crystalline phase  This principle has already been successfully employed in three generations  This principle has already been successfully employed in three generations of rewriteable (RW) optical data storage ( CD, DVD, BD )

14. Pandian et al., Adv. Materials 2007

15. Pandian et al.,Adv. Materials 2007

16. resonance bonds  Crystallization is accompanied by the formation of resonance bonds  Change of bonding mechanism affects the optical properties in the visible & UV range  So far no other materials have similar change of optical properties upon crystallization generates of a large amount of free carriers affecting the IR range  Crystallization generates of a large amount of free carriers affecting the IR range

17. was coined as resonant bonding by Pauling. The situation in which a single, half-filled p-band forms two bonds to the left and right more than allowed by the 8-N rule (N valence) was coined as resonant bonding by Pauling. a fingerprint of resonance bonding electron delocalization characterizing resonant bonding  increased electronic polarizability - a fingerprint of resonance bonding

18. Resonant bonding Free carriers /Drude  relevant for optical data storage: photon energies between  1.5 eV (compact discs) - 3 eV (blu-ray disk) are employed

19. Phys. Rev. A 2010, New Scientist July 2, 2010 (interview with Eugene Reich)

20. Casimir force upon crystallization is due to the change of the dielectric function in the infrared regime (free carriers) ……?in the infrared regime (free carriers) ……? or in the visible-UV range (resonance bonding)….?or in the visible-UV range (resonance bonding)….? Or both and how much they contribute ?Or both and how much they contribute ?

21. Extrapolation  Crystalline PCM: free carriers in many cases (  10 20 /cm 3 )  But have very small mean free paths, even below  3 nm

23. We substracted form the crystalline phase the Drude contribution…….

24. Two strategies to maximize the force contrast upon crystallization of phase change materials: employ materials with particularly strong resonant bonds (PCM with low iconicity and low hybridization of s- and p-states) employ materials with particularly strong resonant bonds (PCM with low iconicity and low hybridization of s- and p-states) small disorder and large carrier concentration to ensure a large Drude contribution small disorder and large carrier concentration to ensure a large Drude contribution

25. …plethora of issues to be resolved to make a device…..

26. Take roughness contributions for both Casimir and electrostatic forces……

27. Broer et al, EPL 2011, PRB 2012

29. Flat surface Pertubative term Peak contribution

31. : Bifurcation parameter in certain situations typically two equilibria occur: a stable center around which periodic solutions exist, unstable saddle point =0 (z)=(1-z/L o )(F L (L o )/F Cas (z) [ (z)/ cas-1]Fcas(z)=0 (z)/= cas

32. Stable region L o =100 nm

34.  Surface roughness can benefit systems against stiction/pull-in instabilities (see poster W. Broer)................take into account hydrodynamic forces for rough surfaces... Work in progress  Surface roughness strongly influences actuation dynamics and proper roughening can benefit systems against stiction/pull-in instabilities (see poster W. Broer)................take into account hydrodynamic forces for rough surfaces... Work in progress PCMS are promissing Two strategies to maximize force contrast of PCMs:  PCMS are promissing for Casimir engines.....more research is needed to fabricate materials to have larger force contrast - Two strategies to maximize force contrast of PCMs: employ materials with particularly strong resonant bonds (low ionicity and low s-p hybridization) employ materials with particularly strong resonant bonds (low ionicity and low s-p hybridization) small disorder and large carrier concentration to ensure a large Drude contribution small disorder and large carrier concentration to ensure a large Drude contribution