Kapteyn-Murnane Group Angle Resolved Photoemission

Angle Resolved Photoemission

Uncovering new electron-electron and electron-phonon couplings and new phases in quantum materials.

Uncovering new electron-electron and electron-phonon couplings and new phases in quantum materials.听(top) in 1T-TaSe2, the electron temperature is significantly modulated by the coherent amplitude mode. (bottom) Distinguishing charge screening and electron-electron scattering in materials. Here we used atto-ARPES to measure photoelectron lifetimes that span from few-attoseconds to ~300 attoseconds.听

Capturing and manipulating dynamic electronic order, phases and couplings in quantum materials

High harmonics are ideal as the illumination source for time- and angle-resolved photoemission spectroscopy (trARPES), which can measure the full electronic band structure of a material. Moreover, a new generation of ultrafast (~50-100fs), MHz rep rate, VUV (1-20eV) highly-cascaded high harmonics driven by compact fiber lasers have 10-100meV energy resolution, and are ideal for spin-resolved ARPES (Optica听7, 832 (2020)).

HHG-based ARPES can not only measure the full electronic band structure - but can also extract the dynamic electron temperature. This is very useful since electrons react very quickly upon excitation by light, on attosecond to femtosecond timescales. Moreover, their heat capacity is small compared to the total heat capacity of the material. After excitation by the laser, the excited electrons rapidly establish a hot Fermi-Dirac distribution within ~20 fs. The energy then gradually flows from the hot electrons to the phonon bath on few ps timescales. This decoupling of excitations and interactions in the time domain means that by measuring the dynamic electron temperature, we can sensitively detect changes in the microscopic interactions within a material, such as electron-phonon couplings or phase changes 鈥 that are indicated by either a change in slope of, or jump in, the electron temperature as a function of excitation laser fluence. When coupled with the ability of HHG trARPES to simultaneously capture the full dynamic band structure (which reflects the macroscopic order parameter), we can map and expand the phase diagram using light as a tuning parameter to uncover new understandings of phase transitions as well as new hidden phases in strongly-coupled materials.

Using this new ultrafast electron calorimetry technique,[1鈥5] we made a number of new observations of how ultrafast lasers can be used to delicately manipulate materials properties, to uncover a fundamental new understanding of phase transitions and interactions in strongly-coupled quantum materials. The new behavior observed appears to be universal in many materials and therefore opens up routes for coherently manipulating the interactions and properties of 2D and other quantum materials using light. In one finding, we uncovered a new metastable phase in a charge density wave (CDW) material, that is characterized by a heat capacity of only ~1/3 of the normal material. In another finding, by monitoring the electron temperature as a function of laser fluence, we uncovered a new metastable CDW state in 1T-TaSe2, and found that it is possible to manipulate the electron-phonon couplings by varying the laser excitation. We also found that the electron temperature is significantly modulated by the coherent amplitude mode by between 200 and 1000 K鈥攚hich represents a new discovery, since in all observations to date, the electron temperature in femtosecond-laser-excited systems decreases monotonically as the electron bath loses energy to the lattice.

Related Publications
  1. Y. Zhang, X. Shi, W. You, Z. Tao Y. Zhong, F. Cheenicode Kabeer, P. Maldonado, P. M. Oppeneer, M. Bauer, K. Rossnagel, H. Kapteyn, M. Murnane,听鈥淐oherent modulation of the electron temperature and electron-phonon couplings in a 2D material,鈥听PNAS 117, 8788 (2020).听
  2. X. Shi, C.-T. Liao, Z. Tao, E. Cating-Submaramanian, M. M. Murnane, C. Hern谩ndez-Garc铆a, H. C. Kapteyn,听鈥淎ttosecond light science and its application for probing quantum materials,鈥听Invited paper, JPhys Photonics/JPhys B Attosecond focus issue听53, 184008 (2020).听
  3. X. Shi, W. You, Y. Zhang, Z. Tao, P. Oppeneer, X. Wu, R. Thomale, K. Rossnagel, M. Bauer, H. Kapteyn, M. Murnane,听鈥淯ltrafast electron calorimetry uncovers a new long-lived metastable state in 1T-TaSe2听mediated by mode-selective electron-phonon coupling,鈥听Science Advances 5, eaav4449 (2019).听
  4. W. You, P.听 Tengdin, C. Chen, X. Shi, D. Zusin, Y. Zhang, C. Gentry, A. Blonsky, M. Keller, P. M. Oppeneer, H. Kapteyn, Z. Tao, M. Murnane,听鈥淩evealing the nature of the ultrafast magnetic phase transition in Ni by correlating extreme ultraviolet magneto-optic and photoemission spectroscopies,鈥听Physical Review Letters听121, 077204 (2018).听
  5. C. Chen, Z. Tao, A. Carr, P. Matyba, T. Szilv谩si, S. Emmerich,听 M. Piecuch, , M. Keller, D. Zusin, S. Eich, M. Rollinger, W. You, S. Mathias, U. Thumm, M. Mavrikakis, M. Aeschlimann, P. Oppeneer, H. Kapteyn, M. Murnane,听鈥淒istinguishing attosecond electron-electron scattering and screening in transition metals,鈥听PNAS 114 (27) E5300鈥揈5307 (2017).听
  6. S. Eich, M. Pl枚tzing, M. Rollinger, S. Emmerich, R. Adam, C. Chen, H. C. Kapteyn, M. M. Murnane, L. Plucinski, D. Steil, B. Stadtm眉ller, M. Cinchetti, M. Aeschlimann, C. M. Schneider, S. Mathias,听鈥淏and-structure evolution during the ultrafast ferromagnetic-paramagnetic phase transition in cobalt,鈥听Science Advances 3, e1602094 (2017).听
  7. Z. Tao, C. Chen, T. Szilvasi, M. Keller, M. Mavrikakis, H. Kapteyn, M. Murnane, 鈥Direct time-domain observation of attosecond final-state lifetimes in photoemission from solids,鈥听Science 353, 62 (2016).听听 See Science Perspective on this work,听Science听353, 28 (2016).
  8. J. Miao, T. Ishikawa, I. K. Robinson, M. M. Murnane,听鈥淏eyond crystallography: Diffractive imaging using coherent X-ray light sources,鈥听Science 348, 530 (2015).听听Featured on cover of Science.
  9. P. Matyba, A. Carr, C. Chen, D. L. Miller, G. Peng, S. Mathias, M. Mavrikakis, D. S. Dessau, M. W. Keller, H. C. Kapteyn, M. Murnane, 鈥淐ontrolling the electronic structure of graphene using surface-adsorbate interactions,鈥 Physical Review B Rapid Communication 92, 041407(R) (2015). DOI: 10.1103/PhysRevB.92.041407
  10. 鈥塜. Yang, G. Rohde, T. Rohwer, A. Stange, K. Hanff, C. Sohrt, L. Rettig, R. Cort茅s, F. Chen, D.鈥塋. Feng, T. Wolf, B. Kamble, I. Eremin, T. Popmintchev, M.鈥塎. Murnane, H.鈥塁. Kapteyn, L. Kipp, J. Fink, M. Bauer, U. Bovensiepen, and K. Rossnagel听听听Physical Review Letters听112, 207001 (2014).听
  11. S. Eich, A. Stange, A.V. Carr, J. Urbancic, T. Popmintechev, M. Wiesenmayer, K. Jansen, A. Ruffing, S. Jakobs, T. Rohwer, S. Hellmann, C. Chen, P. Matyba, L. Kipp, K. Rossnagel, M. Bauer, M. M. Murnane, H. C. Kapteyn, S. Mathias, M. Aeschlimann,听鈥Time- and angle-resolved photoemission spectroscopy with optimized high-harmonic pulses using frequency-doubled Ti:Sapphire lasers,鈥Journal of Electron Spectroscopy and Related Phenomena 195, 231鈥236 (2014).听
  12. S. Hellmann, T. Rohwer, M. Kall盲ne, K. Hanff, C. Sort, A. Stange, A. Carr, M. M. Murnane, H. C. Kapteyn, L. Kipp, M. Bauer and K. Rossnagel,听鈥淭ime-domain classification of charge-density-wave insulators,鈥 Nature Communications 3, 1069 (2012).听听
  13. L. Miaja-Avila, J. Yin, S. Backus, G. Saathoff, M. Aeschlimann, M. M. Murnane, and H. C. Kapteyn,听鈥淯ltrafast studies of electronic processes at surfaces using the laser-assisted photoelectric effect with long-wavelength dressing light,鈥听Physical Review A 79, 030901(R) (2009).听
  14. G. Saathoff, L. Miaja-Avila, M. Aeschlimann, M. M. Murnane, and H. C. Kapteyn,听鈥淟aser-assisted photoemission from surfaces,鈥听Physical Review A 77, 022903 (2008).听
  15. L. Miaja-Avila, G. Saathoff, S. Mathias, J. Yin, C. La-o-vorakiat, M. Bauer, M. Aeschlimann, M. M., H. C. Kapteyn,听鈥淒irect measurement of core-level relaxation dynamics on a surface-adsorbate system,鈥听Physical Review Letters 101, 046101 (2008).听
  16. S. Mathias, L. Miaja-Avila, M. M. Murnane, H. Kapteyn, M. Aeschlimann, M. Bauer,听鈥淎ngle-resolved photoemission spectroscopy with a femtosecond high harmonic light source using a two-dimensional imaging electron analyzer,鈥听RSI 78, 083105 (2007).听听听听听听听听听听听听听听听听听听听