External losses in photoemission from strongly correlated quasitwodimensional solids
(2001) In Physical Review B 64(11). Abstract
 Expressions are derived for photoemission, which allow experimental electron energy loss data to be used for estimating losses in photoemission. The derivation builds on new results for dielectric response and mean free paths of strongly correlated systems of twodimensional layers. Numerical evaluations are made for Bi2Sr2CaCu2O8 (Bi2212) by using a parametrized loss function. The mean free path for Bi2212 is calculated and found to be substantially larger than obtained by Norman et al. [Phys. Rev. B 59, 11 191 (1999)] in a recent paper. The photocurrent is expressed as the convolution of the intrinsic approximation for the current from a specific twodimensional layer with an effective loss function. This effective loss function is the... (More)
 Expressions are derived for photoemission, which allow experimental electron energy loss data to be used for estimating losses in photoemission. The derivation builds on new results for dielectric response and mean free paths of strongly correlated systems of twodimensional layers. Numerical evaluations are made for Bi2Sr2CaCu2O8 (Bi2212) by using a parametrized loss function. The mean free path for Bi2212 is calculated and found to be substantially larger than obtained by Norman et al. [Phys. Rev. B 59, 11 191 (1999)] in a recent paper. The photocurrent is expressed as the convolution of the intrinsic approximation for the current from a specific twodimensional layer with an effective loss function. This effective loss function is the same as the photocurrent from a core level stripped of the dipole matrix elements. The observed current is the sum of such currents from the first few layers. The correlation within one layer is considered as a purely twodimensional (2D) problem separate from the embedding threedimensional (3D) environment. When the contribution to the dielectric response from electrons moving in 3D is taken as diagonal in q space, its effect is just to replace bare Coulomb potentials in the (3D) coupling between the 2D layers with dynamically screened ones. The photoelectron from a specific CuO layer is found to excite lowenergy acoustic plasmon modes due to the coupling between the CuO layers. These modes give rise to an asymmetric powerlaw broadening of the photocurrent an isolated twodimensional layer would have given. We define an asymmetry index where a contribution from a Luttinger line shape is additive to the contribution from our broadening function. Already the loss effect considered here gives broadening comparable to what is observed experimentally. Our theory is not related to the loss mechanism recently discussed by Joynt [R. Joynt, Science 284, 777 (1999); R. Haslinger and R. Joynt, J. Electron Spectrosc. Relat. Phenom. 117118, 31 (2001)] which adds additional broadening beyond what we calculate. A superconductor with a gapped loss function is predicted to have a peakdiphump line shape similar to what has been observed, and with the same qualitative behavior as predicted in the recent work by Campuzano et al. [Phys. Rev. Lett. 83, 3709 (1999)].(35 refs) (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/8812670
 author
 Hedin, Lars ^{LU} and Lee, J. D.
 organization
 publishing date
 2001
 type
 Contribution to journal
 publication status
 published
 subject
 in
 Physical Review B
 volume
 64
 issue
 11
 publisher
 American Physical Society
 external identifiers

 scopus:0035884314
 ISSN
 1550235X
 DOI
 10.1103/PhysRevB.64.115109
 language
 English
 LU publication?
 yes
 id
 fd7cfd2f68284748a7664685bfd87692 (old id 8812670)
 date added to LUP
 20160301 09:46:40
 date last changed
 20170101 07:42:17
@article{fd7cfd2f68284748a7664685bfd87692, abstract = {Expressions are derived for photoemission, which allow experimental electron energy loss data to be used for estimating losses in photoemission. The derivation builds on new results for dielectric response and mean free paths of strongly correlated systems of twodimensional layers. Numerical evaluations are made for Bi2Sr2CaCu2O8 (Bi2212) by using a parametrized loss function. The mean free path for Bi2212 is calculated and found to be substantially larger than obtained by Norman et al. [Phys. Rev. B 59, 11 191 (1999)] in a recent paper. The photocurrent is expressed as the convolution of the intrinsic approximation for the current from a specific twodimensional layer with an effective loss function. This effective loss function is the same as the photocurrent from a core level stripped of the dipole matrix elements. The observed current is the sum of such currents from the first few layers. The correlation within one layer is considered as a purely twodimensional (2D) problem separate from the embedding threedimensional (3D) environment. When the contribution to the dielectric response from electrons moving in 3D is taken as diagonal in q space, its effect is just to replace bare Coulomb potentials in the (3D) coupling between the 2D layers with dynamically screened ones. The photoelectron from a specific CuO layer is found to excite lowenergy acoustic plasmon modes due to the coupling between the CuO layers. These modes give rise to an asymmetric powerlaw broadening of the photocurrent an isolated twodimensional layer would have given. We define an asymmetry index where a contribution from a Luttinger line shape is additive to the contribution from our broadening function. Already the loss effect considered here gives broadening comparable to what is observed experimentally. Our theory is not related to the loss mechanism recently discussed by Joynt [R. Joynt, Science 284, 777 (1999); R. Haslinger and R. Joynt, J. Electron Spectrosc. Relat. Phenom. 117118, 31 (2001)] which adds additional broadening beyond what we calculate. A superconductor with a gapped loss function is predicted to have a peakdiphump line shape similar to what has been observed, and with the same qualitative behavior as predicted in the recent work by Campuzano et al. [Phys. Rev. Lett. 83, 3709 (1999)].(35 refs)}, articleno = {115109}, author = {Hedin, Lars and Lee, J. D.}, issn = {1550235X}, language = {eng}, number = {11}, publisher = {American Physical Society}, series = {Physical Review B}, title = {External losses in photoemission from strongly correlated quasitwodimensional solids}, url = {http://dx.doi.org/10.1103/PhysRevB.64.115109}, volume = {64}, year = {2001}, }