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SOLID STATE SPECTROSCOPY SUMMER TERM 2014 Prof. Dr. Bernhard Keimer Dr. Mathieu Le Tacon 07/04/2014Solid State Spectroscopy.

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Presentation on theme: "SOLID STATE SPECTROSCOPY SUMMER TERM 2014 Prof. Dr. Bernhard Keimer Dr. Mathieu Le Tacon 07/04/2014Solid State Spectroscopy."— Presentation transcript:

1 SOLID STATE SPECTROSCOPY SUMMER TERM 2014 Prof. Dr. Bernhard Keimer keimer@fkf.mpg.de Dr. Mathieu Le Tacon m.letacon@fkf.mpg.de 07/04/2014Solid State Spectroscopy - Introduction1 http://www.fkf.mpg.de/1786169/Teaching

2 Solid State Spectroscopy - Introduction2 Objective of this lecture Provide a general background on some of the experimental spectroscopic techniques that are most commonly used to study materials Provide a general background on some of the experimental spectroscopic techniques that are most commonly used to study materials -Optical Spectroscopy (absorption/reflectivity/ellipsometry) -Inelastic light scattering (Raman, Inelastic X-ray Scattering) -X-ray absorption Spectroscopy (XAS) -Nuclear Magnetic Resonance (NMR) -Inelastic Neutron Scattering (INS) -Tunneling Spectroscopy (STM/STS) -Angle Resolved Photoemission Spectroscopy (ARPES) etc… -Optical Spectroscopy (absorption/reflectivity/ellipsometry) -Inelastic light scattering (Raman, Inelastic X-ray Scattering) -X-ray absorption Spectroscopy (XAS) -Nuclear Magnetic Resonance (NMR) -Inelastic Neutron Scattering (INS) -Tunneling Spectroscopy (STM/STS) -Angle Resolved Photoemission Spectroscopy (ARPES) etc…

3 07/04/2014Solid State Spectroscopy - Introduction3 Non-exhaustive bibliography

4 SOLID STATE … 07/04/2014Solid State Spectroscopy - Introduction4 Material Science Technological applications New materials: synthesis/design Original Physical Properties Nature 410, 63 (2001) 2006 2014 MgB 2 www.columbussuperconductors.com http://www.nanowerk.com/news2/green/newsid=34722.php

5 SOLID STATE … 07/04/2014Solid State Spectroscopy - Introduction5 Material Science Technological applications New materials: synthesis/design Original Physical Properties

6 07/04/2014Solid State Spectroscopy - Introduction6 Materials for the future ? Graphene Transition metal oxide superlattices BUT prior to application need to understand fundamental properties http://cdn.phys.org/newman/gfx/news/hires/ 2012/1-interfacesar.jpg http://upload.wikimedia.org/wikipedia/comm ons/9/9e/Graphen.jpg

7 … Spectroscopy ? 07/04/2014Solid State Spectroscopy - Introduction7 http://www.astroclubmarsan.net/nvxsite/atelierspectro.htm

8 From the atomic building block… 07/04/2014Solid State Spectroscopy - Introduction8 Weakly coupled spectator (NMR) -Nucleus : charge Ze + mass spin I ( magnetic moment M I = -g N I ) -Nucleus : charge Ze + mass spin I ( magnetic moment M I = -g N I ) -Electrons : charge e spin S ( magnetic moment M S = -g B S ) -Electrons : charge e spin S ( magnetic moment M S = -g B S )

9 … to the solid 07/04/2014Solid State Spectroscopy - Introduction9 Nuclei: - Lattice structure - Local defects Nuclei: - Lattice structure - Local defects Charge: - Band structure ? - electronic structure of the defects Charge: - Band structure ? - electronic structure of the defects Spin: - Magnetic structure (e.g. ferro-/ anti-ferromagnetic) Spin: - Magnetic structure (e.g. ferro-/ anti-ferromagnetic) STATIC PROPERTIES (GROUND STATE)

10 … to the solid 07/04/2014Solid State Spectroscopy - Introduction10 Nuclei: - individual: diffusion - Collective: phonons Nuclei: - individual: diffusion - Collective: phonons Charge: - Individual (Intra/Interband, Exciton) - Collective (plasmon) - topological (Vortex) Charge: - Individual (Intra/Interband, Exciton) - Collective (plasmon) - topological (Vortex) Spin: - individual: single spin flip - collective: spin waves/magnons - topological: skyrmions Spin: - individual: single spin flip - collective: spin waves/magnons - topological: skyrmions DYNAMIC PROPERTIES (EXCITATIONS) Microscopic origin of THERMODYNAMIC Properties !

11 07/04/2014 Solid State Spectroscopy - Introduction11 Crystal/Magnetic Structure x-ray /Neutrons/NMR What Experimental techniques ? MgB 2 Dynamical properties Charge electrodynamics: optics Phonon (lattice vibrations): optics, Raman, INS, IXS. Shukla, et al. PRL 90, 095506 (2003) Electronic Structure ARPES STM XAS Ab-initio calculation Souma et al. Nature 423 65(2003) Kortus et al.PRL 86 4656(2003)

12 Experimental Method probe Interesting system InteractionResponse Solid State Spectroscopy - Introduction12 Linear response framework: Response = Susceptibility x Perturbation Linear response framework: Response = Susceptibility x Perturbation Intrinsic property of the system

13 Linear Response Theory Assume in the absence of perturbation Consider an observable(Magnetization, Current, Scattering Cross-section etc..) Consider a external perturbation (=weak) Assuming system homogeneity and time translation invariance It is often more convenient (and relevant) to work directly with Fourier transform Solid State Spectroscopy - Introduction13 Important :is directly related to correlation functions

14 The Probes (pertubations) Solid State Spectroscopy - Introduction14 1) Electro-magnetic field 2) Particles Particleelectronpositronsmuonsneutronsproton Mass m e =9,1 ×10 -31 kg m p =9,1 ×10 -31 kg m =1,88 ×10 -28 kg M N =1,675 ×10 -27 kg M P =1,673 ×10 -27 kg Z.M P + (A-Z).M N -E B /c 2 ~Z.M P + (A-Z).M N -E B /c 2 Charge-e+e-e0+e+Ze± ne Spin1/2 0 if Z and A are even S > 1/2 for 75% of isotopes Depends on n ( e >> Nucleus ) (Internal probe)

15 PerturbationResponding Observable ? Associated Susceptibility corresponding Correlations Magnetic Field H Magnetization M Magnetic Susceptibility m Spin-spin (static/uniform) Spin of NeutronsMagnetic Scattering Cross section S(q, ) Magnetic Susceptibility m (q, ) Spin-spin (non-uniform) Electric Field E Polarization PCharge Susceptibility (q=0, ) Charge-charge (static/uniform) Electric Field E Electrical current jElectrical conductivity q=0, Current-current (uniform) Electric Field E (x-ray beam) Scattering Cross section S(q, ) Charge Susceptibility (q, ) Charge-charge (non-uniform) NMR/ESR/ SR Neutron Scattering Raman Optics X-ray scattering Solid State Spectroscopy - Introduction15

16 Experimental techniques: absorption Interesting system Ground State Incident photon Excited State Solid State Spectroscopy - Introduction16 e.g. NMR B = 0 B 0 I Z = -1/2 I Z = 1/2 E ~ n ħ B loc with n ~ few 10 MHz B loc : local field at the nucleus position Includes surrounding e- through hyperfine coupling e.g. light absorption (dipolar selection rules J = 0, ±1) Kortus et al.PRL 86 4656(2003)

17 Experimental techniques: Luminescence Interesting system Ground State Incident stimulus (photon/electron) Excited State Solid State Spectroscopy - Introduction17 Emitted photon

18 Experimental techniques: Photo-emission Interesting system Ground State Incident Photon Excited State Solid State Spectroscopy - Introduction18 Photo-electron Moser et al. NJP 16 013008 (2013) Analysis of energy and momentum of the photo-electron allows to map out the band structure (here Ba 2 IrO 4 )

19 Experimental techniques: Scattering Interesting system Ground State Incident Particule (photon/electron/neutron) Excited State Solid State Spectroscopy - Introduction19 Distinct from luminescence ! Scatterd Particule Can be - elastic (without loss/gain of energy) e.g. Diffraction - inelastic e.g. Raman scattering, inelastic neutron scattering (INS) - coherent (e.g. diffraction) - incoherent (e.g. Compton scattering) Can be - elastic (without loss/gain of energy) e.g. Diffraction - inelastic e.g. Raman scattering, inelastic neutron scattering (INS) - coherent (e.g. diffraction) - incoherent (e.g. Compton scattering)

20 The Probes Solid State Spectroscopy - Introduction20 1) Electro-magnetic field

21 Solid State Spectroscopy - Introduction21 AbsorptionNMRESRIRPhotoemissionXAS ScatteringRamandiffraction IXS/RIXS http://www.itst.ucsb.edu/~vinhnguyen/VNAPIC/VDI-12.jpg

22 Wavenumber Frequency Energy Temperature FrequencyEnergyTemperature Appendix: the units

23 Solid State Spectroscopy - Introduction23 AbsorptionNMRESRIRPhotoemissionXAS ScatteringRamandiffraction IXS/RIXS http://www.itst.ucsb.edu/~vinhnguyen/VNAPIC/VDI-12.jpg

24 Photon Sources to cover the entire spectral range Solid State Spectroscopy - Introduction24

25 Blackbody radiation Solid State Spectroscopy - Introduction25 Continuous source in the near IR - visible range Limitation: Temperature W wire

26 Lamps Solid State Spectroscopy - Introduction26 Higher temperature emitters: ionized plasma up to 6000 K: Visible Low pressure: discrete spectral lines High pressure : continuum http://www.olympusmicro.com/primer/lightandcolor/lightsourcesintro.html http://www.photonics.com/images/Web/Articles/2010/10/8/HamamatsuFig1.jpg

27 L.A.S.E.R. (Light Amplification by Stimulated Emission of Radiation) https://lasers.llnl.gov/ Solid State Spectroscopy - Introduction27

28 L.A.S.E.R. (Light Amplification by Stimulated Emission of Radiation) Solid State Spectroscopy - Introduction28 1 2 and allow to retrieve Plancks law Equilibrium:

29 L.A.S.E.R. (Light Amplification by Stimulated Emission of Radiation) Solid State Spectroscopy - Introduction29 en.wikipedia.org/wiki/Laser

30 Solid State Spectroscopy - Introduction30 So far IR-visible-UV sources: a few orders of magnitude Photon carries energy AND momentum c = 299 792 458 m s -1 1 eV = 1.602 x 10 -19 J Solid in the real space a b a* b* Solid in the reciprocal space Visible light only probes the center of the reciprocal space ! Equivalently >> a No information at the atomic scale All unit cells are in phase

31 Brighter Photon Sources: Synchrotrons Solid State Spectroscopy - Introduction31 Radiation of a relativistic accelerated charge www.synchrotron-soleil.fr/

32 Brighter Photon Sources: Synchrotrons Solid State Spectroscopy - Introduction32 Measuring the quality of the photon source: Brilliance Size of the source Beam angular divergence

33 Solid State Spectroscopy - Introduction33 X-ray tube 3 rd Generation synchrotron (soft) 3 rd Generation synchrotron (hard) ESRF LCLS Free electron lasers 2 nd Generation synchrotron NSLS

34 http://www.veqter.co.uk/residual-stress-measurement/synchrotron-diffraction A world of synchrotrons Solid State Spectroscopy - Introduction34


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