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5/27/20161 Hard X-ray Photoelectron Spectroscopy (HAXPES) Of Correlated Materials A. Chainani, 1,2 Y. Takata, 1 * M. Oura, 2 M. Taguchi, 3 M. Matsunami,

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Presentation on theme: "5/27/20161 Hard X-ray Photoelectron Spectroscopy (HAXPES) Of Correlated Materials A. Chainani, 1,2 Y. Takata, 1 * M. Oura, 2 M. Taguchi, 3 M. Matsunami,"— Presentation transcript:

1 5/27/20161 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 5/27/20162

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 5/27/20164 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 5/27/20165 Outline 1)Introduction 2)Experimental Setup, Performance & Characteristics 3)Applications : Strongly correlated electron systems 4) Future directions 5) Summary

6 5/27/20166 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 5/27/20167 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 5/27/20168 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 5/27/20169 Small photoionization Cross Sections Obstacle to development of HAXPES Rapid decrease! ~ 1/100 1keV 8keV

10 5/27/201610 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 5/27/201611 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 5/27/201613 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 5/27/201614 Optics Layout for the HAXPES experiments

15 5/27/201615 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 5/27/201616 P. Torelli et al., Rev. Sci. Instrum. 76, 023909 (2005) VOLPE @ ESRF

17 5/27/201617 F. Schafers et al., Rev. Sci. Instrum. 78, 123102 (2007) KMC-1@ BESSY-II

18 5/27/201618 Au 4f core levels @ BESSY-II

19 5/27/201619 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 5/27/201620 Effect of Grazing Incidence of X-rays see also V Strocov, condmat/2013

21 5/27/201621 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 5/27/201622 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 5/27/201623 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)

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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)

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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 5/27/201629 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 5/27/201637 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 5/27/201638 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 5/27/201639 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 5/27/201640 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 5/27/201641

42 Nature Materials 4,173(2005) Carriers : hydrogenic type 5/27/201642

43 Core level spectra Al K  XPS J W Quilty et al PRL 96, 027202(2006) T. Ohtsuki et al PRL 106, 047602(2011) 5/27/201643

44 Valence band spectra CoO/Co metal J W Quilty et al PRL 96, 027202(2006) 5/27/201644

45 J. Woicik et al Phys. Rev. Lett. 89, 077401(2002) 5/27/201645

46 Co 2p-3d XAS 5/27/201646

47 Co 2p-3d Resonant PES 5/27/201647

48 Ti 2p-3d Resonant PES Coherent + Incoherent feature T. Ohtsuki et al PRL 106, 047602(2011) 5/27/201648

49 5/27/201649

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) 5/27/201650

51 5/27/201651 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

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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

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63 5/27/201663 A X Gray et al, Nature Materials, 11, 957(2012) Bulk electronic structure of Ga 1-x Mn x As

64 5/27/201664 Bulk electronic structure of Ga 1-x Mn x As A X Gray et al, Nature Materials, 11, 957(2012)

65 5/27/201665 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 5/27/201666 Y Takashima et al Nature Commun. Dec 2012 DOI:10.1038/ncomms2280

67 5/27/201667 Irene Chen et al., Advanced Functional Materials 22, 2535(2012)

68 5/27/201668 HAXPES has become a valuable tool ! SPring-8 (6 beamlines, not dedicated) ESRF BNL BESSY II SOLEIL PETRA III ERL ? …..

69 5/27/201669 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 5/27/201670


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