1. 1/15/20151 Hard X-ray Photoelectron Spectroscopy (HAXPES) Of Correlated Materials A. Chainani, 1,2 Y. Takata, 1 * M. Oura, 2 M. Taguchi, 3 M. Matsunami, 3 R. Eguchi, 3 S. Shin, 3 1 Coherent X-ray Optics Lab 2 Advanced Photon Technology Division 3 Soft X-ray Spectroscopy Lab RIKEN Harima Institute @ SPring-8 *deceased

2. 1/15/20152

3. 3 Acknowledgements For the development of HAXPES @ BL29XU Coherent X-ray Optics Lab. @ RIKEN SPring8 Center M. Yabashi, K. Tamasaku, Y. Nishino, D. Miwa, T. Ishikawa JASRI/SPring-8 E. Ikenaga (BL47XU), K. Kobayashi （ BL15XU, NIMS) HiSOR, Hiroshima Univ. M. Arita, K. Shimada, H. Namatame, M. Taniguchi Musashi Inst. Technology H. Nohira, T. Hattori (Tohoku Univ.) VG SCIENTA

4. 1/15/20154 Acknowledgements For Collaborations Titanates H. Hwang, H. Takagi Vanadates H. Hwang, K Motoya, Z Hiroi Manganites M. Oshima, Y. Tokura Cobaltates E. Takayama-Muromachi Cuprates T. Mochiku, K Hirata Ruthenates A. Yamamoto Ce compounds H. Sugawara Yb compounds N. Tsujii, A. Ochiai, S Nakatsuji Nitrides K. Takenaka

5. 1/15/20155 Outline 1)Introduction 2)Experimental Setup, Performance & Characteristics 3)Applications : Strongly correlated electron systems 4) Future directions 5) Summary

6. 1/15/20156 Main Characteristic of HAXPES IMFPs 1-4nm @ 1 keV 7-20nm @ 8 keV Inelastic Mean Free Path (IMFP) of Electron (From NIST Database) 30Å （ SiO 2 ) 210Å （ SiO2) 140Å (SiO2) Al K  Bulk sensitive Free from surface prep. Functional thin films Chemical depth analysis Embedded interfaces (non destructive) Large probing depth!

7. 1/15/20157 Early HAXPES with Cu K  @8keV S. Hagstrom, C. Nordlimg, Chuck Fadley, S. Hagstrom, J. Hollander, K. Siegbahn, Phys. Lett. 9, 235 (1964) M. Klein, D. A. Shirley, Science 157, 1571 (1967)

8. 1/15/20158 The first HAXPES with SR I. Lindau, P. Pianetta, S. Doniach & W E Spicer, Nature 250, 214 (1974) Au 4f core level: possible valence band: impossible

9. 1/15/20159 Small photoionization Cross Sections Obstacle to development of HAXPES Rapid decrease! ~ 1/100 1keV 8keV

10. 1/15/201510 High-energy Ce-3d photoemission: Bulk properties of CeM2 (M=Fe,Co,Ni) and Ce7Ni3 L. Braicovich, N. B. Brookes, C. Dallera, M. Salvietti, and G. L. Olcese Phys. Rev. B 56, 15047 (1997) @ESRF High-energy resonant photoemission and resonant Auger spectroscopy in Ce-Rh compoundsHigh-energy resonant photoemission and resonant Auger spectroscopy in Ce-Rh compounds @ESRF P. Le Fèvre, H. Magnan, D. Chandesris, J. Vogel, V. Formoso, and F. Comin Phys. Rev. B 58, 1080 (1998) Hybridization and Bond-Orbital Components in Site-Specific X-Ray Photoelectron Spectra of Rutile TiO2Hybridization and Bond-Orbital Components in Site-Specific X-Ray Photoelectron Spectra of Rutile TiO2 @NSLS J. C. Woicik, E. J. Nelson, Leeor Kronik, Manish Jain, James R. Chelikowsky, D. Heskett, L. E. Berman, and G. S. Herman, Phys. Rev. Lett. 89, 077401 (2002) Quadrupolar Transitions Evidenced by Resonant Auger SpectroscopyQuadrupolar Transitions Evidenced by Resonant Auger Spectroscopy @HASYLAB J. Danger, P. Le Fèvre, H. Magnan, D. Chandesris, S. Bourgeois, J. Jupille, T. Eickhoff, and W. Drube, Phys. Rev. Lett. 88, 243001 (2002) Looking 100 Å deep into spatially inhomogeneous dilute systems with hard x-ray photoemission Looking 100 Å deep into spatially inhomogeneous dilute systems with hard x-ray photoemission @ESRF C Dallera, L. Duò, L. Braicovich, G. Panaccione, G. Paolicelli, B. Cowie, and J. Zegenhagen Appl. Phys. Lett. 85, 4532 (2004) High resolution-high energy x-ray photoelectron spectroscopy using third-generation synchrotron radiation source, and its application to Si-high k insulator systems @SPring8 K. Kobayashi et al. Appl. Phys. Lett. 83, 1005 (2003) A probe of intrinsic valence band electronic structure: Hard x-ray photoemission @SPring8 Y. Takata et al. Appl. Phys. Lett. 84, 4310 (2004) HAXPES for Valence Bands with h = 6 – 8 KeV.

11. 1/15/201511 Experimental Setup

12. How to gain in stability, resoluton, photoelectron intensity 1. High brilliance SR at SPring-8 2. High performance analyzer 3. Top-up injection 4. Matching the detection angle to the polarization of SR magic angle For linearly polarized light, angular intensity distribution of photoemitted electrons depends on the asymmetry parameter   >0 at energies of several keV, for almost all subshells J.Yeh & I.Lindau At. Data.Nucl Data Tables 32, 1(1985) Their intensities have a maximum in a direction parallel to the electric polarization vector 5. Grazing incidence of X-rays IMFP 10nm range e- attenuation length 10  m range X-ray 1 deg. 6. Well-focused X-ray beam 7. Low emittance operation Pol. 55  m(V) 35  m(H) 1deg.

13. 1/15/201513 Experimental setup at BL29XU in SPring-8 ★ excitation energy: 5.95 or 7.94keV,  E (h ): 55 meV ★ photon flux: ~5x10 11 photons/sec @ 55(V)x 35(H)  m 2 ★ analyzer:R4000-10kV (VG Scienta) Y. Takata et al., Nuclear Instrum. and Methods A547, 50 (2005). T. Ishikawa et al., Nuclear Instrum. and Methods A547, 42 (2005). He flow cryostat to reduce sample vibration

14. 1/15/201514 Optics Layout for the HAXPES experiments

15. 1/15/201515 VOLPE @ESRF P. Torelli et al., Rev. Sci. Instrum. 76, 023909 (2005) 30 sec 5 sec High Energy Resolution & High Throughput (at 7.94 keV)  E=55±5 meV (Ep=50 eV) E/  E=140000! 15min

16. 1/15/201516 P. Torelli et al., Rev. Sci. Instrum. 76, 023909 (2005) VOLPE @ ESRF

17. 1/15/201517 F. Schafers et al., Rev. Sci. Instrum. 78, 123102 (2007) KMC-1@ BESSY-II

18. 1/15/201518 Au 4f core levels @ BESSY-II

19. 1/15/201519 Surface Insensitivity SiO 2 /Si(100) @ 7.94keV Contribution of surface SiO 2 is negligible! IMFP: Si=12nm, SiO 2 =16nm @ 8keV Si=1.8nm, SiO 2 =3nm @ 0.85keV 300sec SiO 2 Si 1s BE:1840eV Si 2p BE:100eV 10sec 30sec Si : SiO 2 =42 : 1 SiO 2 contribution < 3% Y. Takata et al. Appl. Phys. Lett. 84, 4310 (2004)

20. 1/15/201520 Effect of Grazing Incidence of X-rays see also V Strocov, condmat/2013

21. 1/15/201521 High Sensitivity (Buried Layer and Interface) SrTiO 3 LaVO 3 :3ML LaAlO 3 :3ML LaAlO 3 :30ML H. Wadati, A. Fujimori, H. Y. Hwang et al., PRB77, 045122 (2008) 5x10 -7 Mb

22. 1/15/201522 Large Probing Depth Sr 2p 3/2 (BE=1940eV) x65 e-e- e-e- La 0.85 Ba 0.15 MnO 3 (20nm) SrTiO 3 H. Tanaka et al., Phys. Rev. B 73, 094403 (2006)

23. 1/15/201523 Applications

24. La 1-x Sr x MnO 3 M-I transition with Colossal magnetoresistance A.Urushibara et al., Phys. Rev. B 51, 14103 (1995) H. Fujishiro et al., J. Phys. Soc. Jpn. 67, 1799 (1998)

26. Feature absent in earlier soft-ray PES A.Chainani et al. Phys. Rev. B 47, 15397 (1993) T.Saitoh et al., Phys. Rev. B 56, 8836 (1997)

28. MO 6 Cluster model calculations Ground state ： linear combination of 6 configurations 3d 6 L 2 3d 6 LC3d 5 C 3d 6 C 2 U   F  O 2p band UH LH １． Intra-atomic multiplets ２． Crystal Field ３． Hybridization between O 2p and Ru 3d orbital : Covalency 4 ． Hybridization between coherent states at E F and Ru 3d orbitals : metallicity 3d 4 3d 5 L M. Taguchi G. Van der Laan et al PRB 23, 4369(1981) J. Imer & E. Wuilloud. Z Phys. B 66, 153 (1987) 21

29. 1/15/201529 Comparison with cluster calculations V* = 0.28V Δ* = 3.6 eV V* = 0.39V Δ* = 4.0 eV V* = 0.425V Δ* = 4.0 eV V* = 0.25V Δ* = 3.0 eV FM AFM FM AFI Good agreement! low BE feature CT from coherent states 2p 5 3d 5 C K. Horiba et al. Phys. Rev. Lett 93, 236401 (2004)

30. V 1.98 Cr 0.02 O 3 (experiments) Metal Insulator K. Smith et al. PRB 50, 1382 (1994) (h = Al K  :1486.7 eV) M. Taguchi et al. PRB 71,155102(2005) (h : 5950 eV)

31. V 2 O 3 VB Photoemission (Coherent Peak) Mo et al. PRL 90, 186403 (2003) Zhang et al. PRL 70, 1666 (1993) Coherent part Incoherent part U DMFT cal.

32. Calculation vs. Experiment  * - U dc | 2p 5 3dL 2p 5 3d 3 C 2p 5 3d 2  -U dc |  ** 3d 3 L 3d 3 C 3d 2 | g >|f > M. Taguchi et al. PRB 71,155102(2005)

33. Hole- and Electron-Doped High-Tc Cuprates La 2 CuO 4 Nd 2 CuO 4 * M. van Veenendaal et al. PRB 49, 1407 (1994) * Ino et al., PRL 79, 2101 (1997) * Harima et al., PRB 64, 220507(R) (2001) * Steeneken et al. PRL 90, 247005 (2003)

34. Background （ doping induced chemical potential shift) Mid-gap pinning scenario Crossing the gap scenario formation of new states within the band gap on doping M. van Veenendaal et al. PRB 49, 1407 (1994)  moves to the top of the valence band by hole-doping and bottom of the conduction band on electron-doping

35. Calculation vs. Experiment  * - U dc | 2p 5 3d 9  -U dc |  ** 3d 10 L 3d 10 C 3d 9 | g >| f > 2p 5 3d 10 L 2p 5 3d 10 C M. Taguchi et al. Phys. Rev. Lett. 95, 17702 ( 2005 ).

36. Cu 2p XPS (Estimated Parameters)   F  O 2p band UH B NCCO   F  O 2p band UHB LSCO

37. 1/15/201537 CT type system: Nd 1.85 Ce 0.15 CuO 4 (NCCO) M. Taguchi et al., Phys. Rev. Lett. 95, 17702 ( 2005 ). 1.5keV 5.9keV See also G. Panaccione et al. PRB 77, 125133 (2008)  U  F  UH LH O 2p band Charge-Transfer type

38. 1/15/201538 Valence Transition of YbInCu 4 800eV 43eV 5950eV See also Suga et al., J. Phys. Soc. Jpn, 78, 074704 (2009) H. Sato et al., Phys. Rev. Lett., 93, 246404 (2004)

39. 1/15/201539 Combining HAXPES with optical spectroscopy Evidence for purely Yb 2+ bulk state, Yb 3+ surface state, and energy-loss satellite due to interband transitions However, the Yb valence estimated by L-edge RIXS & XAS: ~2.08 K. Syassen, Physica B+C 139-140 (1986) 277. ~2.35 E. Annese et al., Phys. Rev. B 70 (2004) 075117. YbS: Ionic crystal Yb 2+ S 2-, hence typical Yb 2+ system  h e-e- optical reflectivity M. Matsunami et al., Phys. Rev. B, 78, 185118(2008)

40. 1/15/201540 Remote hole-doping at an interface M. Takizawa et al., PRL. 102, 236401(2009) V 3+ (bulk) For LaAlO 3 /SrTiO 3, see M. Sing et al. PRL 102, 176805 (2009)

41. Science, 291, 854 (2001) Electronic structure of the room temperature ferromagnet Co:TiO 2 anatase 1/15/201541

42. Nature Materials 4,173(2005) Carriers : hydrogenic type 1/15/201542

43. Core level spectra Al K  XPS J W Quilty et al PRL 96, 027202(2006) T. Ohtsuki et al PRL 106, 047602(2011) 1/15/201543

44. Valence band spectra CoO/Co metal J W Quilty et al PRL 96, 027202(2006) 1/15/201544

45. J. Woicik et al Phys. Rev. Lett. 89, 077401(2002) 1/15/201545

46. Co 2p-3d XAS 1/15/201546

47. Co 2p-3d Resonant PES 1/15/201547

48. Ti 2p-3d Resonant PES Coherent + Incoherent feature T. Ohtsuki et al PRL 106, 047602(2011) 1/15/201548

49. 1/15/201549

50. charge neutrality condition : Co 2+ + V O 2− + 2Ti 4+  Co 2+ + 2Ti 3+ (V O is oxygen vacancy) Surface Science, 601, 5034(2007) 1/15/201550

51. 1/15/201551 correspondence between the well-screened feature and coherent states S. Biermann et al, PRL, 94, 026404, 2005 ; J. M. Tomczak & S. Biermann, J. Phys.: Cond. Matter, 19, 365206, 2007. J. M. Tomczak, F. Aryasetiawan & Silke Biermann, PRB, 78,115103, 2008. See also T. Koethe et al PRL 97, 166402(2006) ; S. Suga et al, New J. Physics 11, 103015 (2009).

52. Hg 2 Ru 2 O 7 and Tl 2 Ru 2 O 7 exhibit first order metal-insulator transitions(MIT) Hg 2 Ru 2 O 7 Tc = 108 K  eff ~3.7  B Ru 5+ Tl 2 Ru 2 O 7 Tc = 125 K  eff ~ 2.8  B Ru 4+ A Yamamoto et al JPSJ(Letters) 4, 043703 (2007) S. Lee et al Nature Materials 5, 471 (2006) W. Klein et al J. Mat. Chemistry 17, 1356 (2007) 2

53. Clear temperature dependence across the MIT

55. CompoundMetallic bonding energy (kcal/mol) Covalent bonding energy (kcal/mol) Reference No. Tl 2 Ru(IV) 2 O 7 12.60 50.73present work Hg 2 Ru(V) 2 O 7 21.68 46.12present work Ti 4 O 7 20.06 66.88 44 VO 2 11.07 55.34 45 V2O3V2O3 17.29 66.88 22 CrN 17.53 62.26 46 La 0.8 Sr 0.2 MnO 3 9.80 67.8030 La 0.85 Ba 0.15 MnO 3 9.22 67.80 47 La 1.85 Sr 0.15 CuO 4 28.83 86.48 24 Nd 1.85 Ce 0.15 CuO 4 41.51 80.71 24 Standard bondenergies C-H bond 99 1 C-C bond 83 1 C-N bond 73 1 Hydrogen bondingin water ~5 1 Van der Waalsbonding ~1 1 Covalency and metallicity of TMCs and some standard bonding energies. A. Chainani et al. PRB 87, 045108 (2013)

56. HAXPES results from our group : Zhang-Rice doublet state in NiO PRL 100 206401(2008) Changes across successive first-order transitions in the Magneli compound Ti 4 O 7 PRL 104,106401(2010) Paramagentic insulator to Anti-ferromagnetic metal transition in CrN PRL 104,236404(2010) Mixed Valency in a quantum critical f-electron system YbAlB 4 PRL 104,247401(2010) Recoil effects of core and valence photoelectron in solids Y. Takata, et al., PRL101, 137601(2008)

57. Recoil effects in PES: C 1s core level spectra of graphite Y. Takata et al., PRB 75, 233404 (2007) KE dependence at normal emission h =7940eV  E=120meV) h =5950eV (  E=120meV) h =870eV  E=100meV) ★ not observed in Au ★ not due to semimetallic character ★ not due to bulk vs surface but due to recoil effect !

58. Recoil effects in core level spectra of other light elements, such as (Be, B, Al)

59. Recoil effects in valence band (Fermi-edge) of Al @ 7.94keV Y. Takata, Y. Kayanuma et al.,Phys. Rev. Lett.101, 137601(2008) M(Au): 197 (m/M)xE: 22meV M(Al): 27.0 (m/M)xE: 160meV  E=119meV 2p:115meV Gaussian width Au:124meV Al: 160meV

60. Theory by Y. Kayanuma, S. Tanaka and S. Oshima Y. Takata, Y. Kayanuma et al.,Phys. Rev. Lett.101, 137601(2008) isotropic Debye model

61. 1/15/201561

62. 1/15/201562

63. 1/15/201563 A X Gray et al, Nature Materials, 11, 957(2012) Bulk electronic structure of Ga 1-x Mn x As

64. 1/15/201564 Bulk electronic structure of Ga 1-x Mn x As A X Gray et al, Nature Materials, 11, 957(2012)

65. 1/15/201565 Future Prospects ★ Improvement of energy resolution to ~10 meV ★ Angle resolved measurements VB mapping Photoelectron diffraction ★ Polarization dependence ★ Atoms and molecules non-dipole effects ★ Dynamics using time resolved HAXPES ★ Application to high vapor pressure systems Liquids/Wet samples/Gels Gray et al Ueda et al Simon et al Castro et al

66. 1/15/201566 Y Takashima et al Nature Commun. Dec 2012 DOI:10.1038/ncomms2280

67. 1/15/201567 Irene Chen et al., Advanced Functional Materials 22, 2535(2012)

68. 1/15/201568 HAXPES has become a valuable tool ! SPring-8 (6 beamlines, not dedicated) ESRF BNL BESSY II SOLEIL PETRA III ERL ? …..

69. 1/15/201569 International WS to Conferences on HAXPES 1 st in 2003 @ ESRF by Zegenhagen 2 nd in 2006@ SPring-8 by Kobayashi and Suga 3 rd in 2009 @ NSLS by Woicik and Fadley 4 th in 2011 @ HASYLAB by Drube 5 th in 2013 @ Uppsala by Svensson and Martensson

70. Thank you very much for your attention 1/15/201570

71. Science 287, 1019 (2000) Mn:GaAs 1/15/201571

72. 1/15/201572

73. Ti 2p HX-PES M. Taguchi et al, PRL 104, 106401 (2010) 1/15/201573

74.  * -U dc | 2p 5 3d 0  -U dc |  ** 3d 1 L 3d 1 C 3d 0 2p 5 3d 1 L 2p 5 3d 1 C CT | g › | f › HT phase 1/15/201574

75. Ti 4+ cluster （ V* =0 ） Ti 3+ Ti 4+ LT phase 1/15/201575

76. 1/15/201576

77. Ti 4+ cluster （ V* =0.3 eV ） Ti 3+ Remnant of Coherent states IT phase 1/15/201577

78. 1/15/201578 SUMMARY Ruthenates with and without orbital order exhibit Mott-Hubbard type band-width controlled metal-insulator transitions The Magneli phase compound Ti 4 O 7 has an anomalous intermediate phase sandwiched between a Fermi liquid and charge ordered insulator Equivalence of screening due to coherent states and non-local screening Accurate Valence determination in d and f electron systems

79. 1/15/201579 Semiconductors : HfO 2 :SiO 2 (K. Kobayashi et al) SiO 2 /Si(100) (Y. Takata et al), GaAs (C. Dallera et al), Cr : GaN( J.J. Kim et al), Si (F. Offi et al), In 2 O 3 (A. Walsh et al), etc. Elements : Co, Cu, Ag, Ni, etc. (M.Sacchi et al, G. Panaccione et al, O. Karis et al) f-electron systems : Ce systems (L. Braicovich et al, P. Fevre et al, M. Matsunami et al) Yb Mixed valence (H. Sato et al, A. Yamasaki et al), Yb Kondo (L. Moreschini et al) Titanates: XSW partial DOS ( J Woicik et al) ; Resonant Auger (J. Danger et al ) Vanadates : Mott-Hubbard transition (N. Kamakura et al, M. Taguchi et al, G. Panaccione et al, J. Woicik et al ) Cobaltates : charge order (A. Chainani et al) Manganites: doping dependence(K. Horiba et al), bilayer (F. Offi et al, S. de Jong et al) T-dependence (H. Tanaka et al, F. Offi et al, S. Ueda et al,) Cuprates : hole and electron doping (M. Taguchi et al, G. Panaccione et al, K. Maiti et al) Iron Pnictides : LaFePO(Y Kamihara et al) ; BaFe2As2 (S. de Jong et al) Nickelates : NiO (J. Woicik et al, M. Taguchi et al) Importance of s-states in a metallic oxide: PbO 2 (D. J. Payne et al) Intermetallics: Huesler alloys ( C. Felser et al) Ruthenate complexes : role of intermolecular interactions ( S Svensson et al) Multilayers: Ni/Cu (Holmstrom et al) Oxide Multilayers : LaAlO3/SrTiO3 (M. Sing et al) ; LaVO3/LaAlO3 (M. Takizawa et al)

80. 1/15/201580 HAXPES has become a standard tool ! SPring-8 (6 beamlines, not dedicated) ESRF NSLS BESSY II SOLEIL APS PETRA III ALS? MAX-IV? …..

81. 1/15/201581 International WS on HAXPES 1 st in 2003 @ ESRF by Zegenhagen 2 nd in 2006@ SPring-8 by Kobayashi and Suga 3 rd in 2009 @ NSLS by Woicik and Fadley 4 th in 2011 @ HASYLAB by Drube 5 th in 2013 @ Uppsala by Svensson and Martensson

82. 1/15/201582 Future Prospects ★ Improvement of energy resolution to ~20 meV ★ Angle resolved measurements VB mapping Photoelectron diffraction ★ Polarization dependence ★ Application to high vapor pressure systems Liquids/Wet samples ★ Atoms and molecules non-dipole effects Recoil & Dynamics Fadley, Papp et al Ueda et al Simon et al Castro et al

83. Thank You very much 1/15/201583

84. Comparison with Nb:STO(SrTiO 3 ) Y. Ishida et al PRL 100, 056401 (2008) 1/15/201584

85. Y. Ishida et al PRL 100, 056401 (2008) 1/15/201585

86. 1/15/201586

87. 1/15/201587

88. Y Aiura et al. Surface Science 515, 61 (2002) 1/15/201588

89. n-type SrTiO 3-  J. Chang et al PRB 81,235109(2010) 1/15/201589

90. Nature 469, 189 (2011) 1/15/201590

91. O K-edge XAS 1/15/201591

92. O K-edge Resonant PES 1/15/201592

93. Constant initial state spectra across the O K-edge 1/15/201593

94. Partial density of states near E F Y. Ishida et al PRL 100, 056401 (2008) 1/15/201594

95. Ti 2p-3d Resonant PES Coherent + Incoherent feature T. Ohtsuki et al PRL 106, 047602(2011) 1/15/201595

96. Cu 2p XPS (experiments) M. A. van Veenendaal and G. A. Sawatzky, Phys. Rev. B 49, 3473 (1994) K. Okada and A. Kotani, J. Electron Spectrosc. Relat. Phenom. 86, 119 (1997). K. Karlsson, O. Gunnarsson and O. Jepsen, Phys. Rev. Lett. 82, 3528 (1999) ; A. Koitzsch et al., Phys. Rev. B 66, 024519 (2002).

97. O 1s XPS (Experiment) Peak shift NCCO LCO  0.25 eV LCOLSCO  0.2 eV Peak shift is rather small as compared with optical gap （  1.0 eV ）

98. O 1s XAS O 1s level UHB LSCO NCCO C. T. Chen et al. Phys. Rev. Lett 66, 104(1991) ; M. Romberg et al. Phys. Rev. B 43, 333(1991)

99. T. Fukumura et al New Journal of Physics 10, 055018 (2008) 1/15/201599

100. Recoil effects in valence band (Fermi-edge) of Al @ 880eV M(Au): 197 (m/M)xE: 2meV M(Al): 27.0 (m/M)xE: 18meV  E=12meV Gaussian width Au:118meV Al: 140meV

101. Our Experiments : Epitaxial films grown by pulsed laser deposition Characterization : Structure and ferromagnetism X-ray Absorption Spectroscopy(XAS) Resonant photoemission(PES) @ BL17  E ~230 meV at Ti L-edge Hard X-ray PES @ BL 29  E ~250 meV at h = 8 KeV 1/15/2015101

102. XRD RHEED Samples : PLD grown films characterized by x-ray diffraction RHEED oscillation RHEED pattern 1/15/2015102

103. New Journal of Physics 10, 055018 (2008) 1/15/2015103

104. 0.8  B/Co T. Fukumura et al New Journal of Physics 10, 055018 (2008) 1/15/2015104

105. Recoil effects in photoelectron emission Theory by Y. Kayanuma & S. Tanaka ( PRB 75, 233404 (2007) ) For an atom in free space  E=(m/M)E  E:recoil energy M: atomic mass m: electron mass E: kinetic energy For C atom at 8 keV m/M=1/22000  E=0.36 eV In graphite  E is absorbed by the phonon bath. Excitation of phonons Mössbauer effect in  -ray emission

106. Theoretical calculation: Debye model Normal emission: h  D =75meV

107. Emission Angle Dependence e-e- Normal emission: h  D =75meV Grazing emission: h  D =150meV Recoil effects in PES reflect phonon dynamics!

108. Comparison of recoil effects in graphite M. Vos, et al., PRB 78, 024301(2008) photoelectron emission electron scattering neutron scattering

109. Comparison between Diamond & Graphite

110. LDA & (LDA + DMFT) of Hg 2 Ru 2 O 7 Importance of multi-orbital correlations negligible influence of spin-orbit coupling 24 L. Craco et al, PRB 79, 075125 (2009)

111. S. Baidya et al, PRB 86, 125117 (2012)

112. A. Chainani et al. PRB 87, 045108 (2013) (3~4

113. 1/15/2015113 Large Probing Depth Sr 2p 3/2 (BE=1940eV) x65 e-e- e-e- La 0.85 Ba 0.15 MnO 3 (20nm) SrTiO 3 Estimation of IMFP value N(z)=N 0 exp(-z/ ) (4keV)=5nm in LBMO surface layer contribution layer distance 0.4nm =1nm: 33% =5nm: 8% =10nm: 4% higher KE larger H. Tanaka et al., Phys. Rev. B 73, 094403 (2006)

114. Be 1s core level of polycrystalline Be Surface Atomic weight: 9.0  E(5950eV)=330meV (m/M)xE: 355meV  E(7940eV)=440meV (m/M)xE: 475meV Surface feature

115. B 1s core level of MgB 2 a bundle of needle crystals supplied by H. Kitoh @NIMS Atomic weight: 10.8  E(5950eV)=240meV (m/M)xE: 290meV  E(7940eV)=340meV (m/M)xE: 390meV

116. Al 2p core level of Al thin film Atomic weight: 27.0  E(5950eV)=90meV (m/M)xE: 120meV  E(7940eV)=115meV (m/M)xE: 160meV

117. 1/15/2015117

118. XMCD synthesis and annealing in oxygen K. Mamiya, T. Koide, A. Fujimori et al, APL 89, 062506 (2006) 1/15/2015118

119. Early spectroscopy : Controversy PRL 90, 017401(2003) 1/15/2015119

120. Ferromagnetism is due to Co clusters postannealing in Vacuum J. Y. Kim et al PRL 90, 017401(2003) 1/15/2015120

121. What is different ? Reducing atmosphere : Co clusters versus Oxidizing atmosphere : Co 2+ Intrinsic ferromagnetism 1/15/2015121

122. EXAFS of Co:TiO 2 1/15/2015122

123. Ti 2p and O 1s core levels 1/15/2015123

124. A. Chainani et al. PRB 87, 045108 (2013) (3~4

126. V 1s core level PES of V 2 O 3 PM (V ∗ = 0.75) T = 250 K AFI (V ∗ = 0) phases. T = 90 K N. Kamakura et al. Europhysics Letters 68, 557(2004)

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