Stanford Synchrotron Radiation Lightsource SSRL x Chi-Chang Kao
BL1-4 BL1-5 BL2-1 BL2-2 BL2-3 BL4-1 BL4-2 BL4-3 BL5-4 BL6-2(3) BL7-1 BL7-2 BL7-3 BL8-1 BL8-2 BL9-1 BL9-2 BL9-3 BL10-1 BL10-2(2) BL11-1 BL11-2 BL11-3 BL12-2 BL13(3) BL14-1 BL14-3 Materials small angle x-ray scattering (SAXS) Macromolecular crystallography Powder diffraction / thin film diffraction Instrument characterization Microprobe / X-ray absorption spectroscopy (XAS) imaging Environmental, materials, chemistry, interfacial science XAS Biological SAXS Biological/Molecular Environmental & Interfacial Science (MEIS) XAS High-resolution photoemission spectroscopy (PES); Angle-resolved photoemission spectroscopy (ARPES) Transmission x-ray microscopy (TXM), advanced x-ray spectroscopy and inelastic scattering, rapid-scan x-ray fluorescence (RS-XRF) imaging Macromolecular crystallography X-ray scattering Biological XAS Core level PES < 200 ev X-ray absorption near edge spectroscopy (XANES) < 1000 ev Macromolecular crystallography Macromolecular crystallography Biological XAS XANES, Core level PES < 1000 ev XAS imaging / X-ray scattering Macromolecular crystallography MEIS XAS Thin film scattering Macromolecular crystallography, micro-crystals Soft x-ray coherent scattering, advanced spectroscopy, scanning transmission x-ray microscopy (STXM) Macromolecular crystallography XAS (2-5keV) (in construction) Beam Lines at SSRL Imaging Scattering 2006 Spectroscopy
Materials Scattering / Diffraction Three multi-circle facilities on wiggler stations with different capabilities as for focus, energy range, detectors and resolution BL7-2: wiggler end station, new in 2004, sagittal monochromator BL11-3: wiggler side station, fixed energy, crystal focusing, area detector (image plate) BL10-2: wiggler end station, toroidal mirror scattered X-rays X-rays
Soft X-ray Spectroscopy End station: Ultra-high energy resolution photoelectron spectrometer Scienta R4000 Chamber has high magnetic shielding; has LHe cryostat with 2-axis rotation New photoemission beam line funded (Z.X. Shen & Donghui Lu) in design Large energy range with circular polarization and MBE sample preparation
SSRL Imaging Facilities SPEAR3 high brightness: new imaging techniques wide range of length scales biological, environmental, and materials science Focused beams using mirrors, capillaries, and apertures X-ray beam sizes over a wide range (10 0-10 2 µm) Beam Lines 2-3, 10-2 and 14-3 Locate and quantify different elements in a wide variety of samples Speciation: chemistry/structure of the element at specific locations Fossils, soils, plants, tissue samples, cells Beam Line 13-1 STXM Zone plates to focus the beam to 40 nm Study properties of magnetic domains Hard X-ray microscope Beam Line 6-2 2- and 3-dimensional images in real space at 30 nm resolution biomaterials such as bones and teeth, advanced fuel cell materials, nanostructures Lensless imaging Beam Line 13-3 Uses 2D pattern of soft x-rays scattered from the sample to image nanostructures Resolutions better than 30 nm
Materials Sciences Themes materials for sustainable energy generation, transformation & storage strongly correlated electron materials & magnetism ultrafast (ps) sciences in-situ growth/synthesis/reactions industrial engagement Five Grand Challenges: control of materials at electron level materials by design emergence & control of complexity master energy & information on the nanoscale to create new technologies characterize & control matter away from equilibrium
Materials for Sustainable Energy materials for sustainable energy generation, transformation & storage: o interfaces o photovoltaics o batteries o nanomaterials for catalysis Why: central to DOE & SLAC mission materials by design connects to PSD, Stanford
Strongly Correlated Electron Materials Strongly correlated electrons high temperature superconductors complex oxides topological insulators magnetic materials Why: world leading ARPES SSRL- Stanford (D Lu, ZX Shen, ). emerging complexity & mastering energy grow scattering in this area: thermal and high pressure, interfaces
Ultrafast (ps) Sciences Ultrafast (ps) Sciences chemical reactions phase transitions non-equilibrium dynamics InP: lattice disorder Why: materials far from equilibrium connects to LCLS & PULSE Trigo and Reis et al.
In-situ Growth/Synthesis In-Situ Materials Growth molecular solids surfaces, topological insulators, spintronics emergent phenomena at interfaces atomic engineering oxide heterostructures nanoparticles (catalysts) atomic layer deposition (ALD) Why: connects to energy materials, strongly correlated electron materials, catalysis broaden ARPES program
Opportunity: Basic - Applied Research Integration Grand Challenges How nature works Controlling materials processes at the level of quantum behavior of electrons Atom- and energyefficient syntheses of new forms of matter with tailored properties Emergent properties from complex correlations of atomic and electronic constituents Man-made nanoscale objects with capabilities rivaling those of living things Discovery and Use-Inspired Basic Research Applied Research Materials properties and chemical functionalities by design Basic research for Basic research, often fundamental new with the goal of understanding on addressing materials or systems showstoppers on realworld applications in the that may revolutionize or transform today s energy technologies energy technologies Development of new tools, techniques, and facilities, including those for the scattering sciences and for advanced modeling and computation Controlling matter very BESAC & BES Basic Research Needs Workshops far away from equilibrium Research with the goal of meeting technical milestones, with emphasis on the development, performance, cost reduction, and durability of materials and components or on efficient processes Proof of technology concepts Technology Maturation & Deployment Scale-up research At-scale demonstration Cost reduction Prototyping Manufacturing R&D Deployment support Synchrotron Covers the Whole Range of Research ESAC Grand Challenges Panel DOE Technology Office/Industry Roadmaps EFRC Kung, BESAC, July 2009
Meeting with Harold s group Soft X-ray Capabilities for Investigating the Heterostructure: XAS, XMCD, and RSXS Jun-Sik Lee Chi-Chang Kao SSRL, SLAC National Accelerator Laboratory
Heterostructure, using transition metal oxides Strongly correlated electronic system interface Interplay Image is taken from Y. Kozuka et al (Nature, 2009) We need to understand such interplay! New functionality
Mostly, perovskite oxides motivates extensive and ongoing research on heterostructures. Example) O K-edge Ti L-edge Local sym.: SrTiO 3 Local sym.: Rutile usually, B-site is 3d transition metal Local sym.: Anatase Directly probe the Oxygen (via K-edge) & the 3d transition metals (via L-edges) Van der Laan, Phys. Rev. B (1990) Sensitive to the local charge state (valence band) & site symmetry (orbital).
Strong resonant effect: Density difference if material has a magnetic behavior Strong magnetic resonance @ Fe L-edge (Example) taken by CXRO Max. ~30% in the resonance (Note) hard x-ray is about 1%
We can carry out for exploring the interplay XAS XMCD RSXS XAS: X-ray Absorption Spectroscopy XMCD: X-ray Magnetic Circular Dichroism RSXS: Resonant Soft X-ray Scattering
a few Examples References J.-S. Lee & C.-C. Kao et al., PRB 80, 180403(R) (2009). S. Smadici & P. Abbamonte et al., PRL 102, 107004 (2009). P. Yu & J.-S. Lee et al., PRL 105, 027201 (2010). J.-S. Lee & C.-C. Kao et al., PRL 105, 257204 (2010). H. W. Jang & C. E. Eom.: Science 331, 886 (2011). J.-S. Lee & C.-C. Kao et al., J.Phys. 23, 256001 (2011). J.-S. Lee & C.-C. Kao et al., PRL 107, 037206 (2011). E. Benckiser et al., Nature Mat. 10, 189 (2011). J.-S. Lee & C.-C. Kao et al., in preparation.
Investigating the interfacial modification Usually, peoples have used a combination of STEM and EELS analysis. (example) SrTiO 3 (10 UC)/LaO(1 ML)/SrTiO 3 Ref.: Science 331, 886 (2011) Synchrotron experiment is non-destructive measurement. Also, it rules out a possibility of a change of the sample (strain and/or irradiation) caused by the TEM-sample preparation. (example) La 0.7 Sr 0.3 MnO 3 / La 1-x Sr x MnO 3 (1UC)/SrTiO 3 heterostructure Ref.: in preparation
Investigating the change distribution, and corresponding orbital state -System- La 0.7 Sr 0.3 MnO 3 /SrTiO 3 heterostructure Ref.: PRL 105, 257204 (2010) K E z z z y x y x y x Photon polarization Large absorption No absorption (ideally)
Investigating the correlation between spin and orbital state -System- La 0.7 Sr 0.3 MnO 3 /BiFeO 3 heterostructure Ref.: PRL 105, 027201 (2010)
Investigating the induced magnetism -example- La 0.7 Sr 0.3 MnO 3 /BiFeO 3 heterostructure Ref.: PRL 105, 027201 (2010) -example- Ta/Co/Cu/Pt/GaAs[001] Spin-Transfer Torque Ref.: PRB 80, 180403(R) (2009)
Investigating the Charge Reconstruction at LaCuO 4 /La 1.64 Sr 0.36 CuO 4 Superlattice Ref.: PRL 102, 107004 (2009) Superlattice s hole distribution ideal real
Investigating the induced Spin moment at Interfaces As-grown structure buried EB structure Al2O3 CoFe IrMn NiFe SiO2 Si (sub.) FM AFM FM Ref.: J.Phys. 23, 256001 (2011) Real magnetic structure
Investigating the induced Spin moment at Interfaces -System- Ta/Co/Cu/Pt/GaAs[001] Spin-Transfer Torque Ref.: PRB 80, 180403(R) (2009)
Investigating the Orbital Reconstruction at LaNiO 3 /LaAlO 3 Superlattice Interfaces Hard x-ray Ref.: Nature Mat. 10, 189 (2011) Ni L 3 -edge Ni L 2 -edge
Investigating the lattice distortion caused by spin and orbital degrees of freedom Ref.: PRL 107, 037206 (2011).
Using non-destructive & element specific x-ray techniques (here Soft x-ray), we can investigate microscopic aspects of heterostructures, especially interface physics! of course if we have a good sample! XAS: BL 8-2, 10-1, & 13-1 XMCD: BL 13-1 RSXS: BL 10-1 (in future)
Soft X-ray Scattering Chamber at NSLS (BNL)