Spin polarization and magnetic dichroism in photoemission from core and valence states in localized magnetic systems. III. Angular distributions

1994 ◽  
Vol 49 (14) ◽  
pp. 9613-9631 ◽  
Author(s):  
B. T. Thole ◽  
Gerrit van der Laan
Keyword(s):  
Spin Polarization ◽  
Angular Distributions ◽  
Magnetic Systems ◽  
Valence States ◽  
Magnetic Dichroism

Observation of multi-channel non-adiabatic dynamics in aniline derivatives using time-resolved photoelectron imaging

2016 ◽  
Vol 194 ◽  
pp. 185-208 ◽  
Author(s):  
Magdalena M. Zawadzki ◽  
Marco Candelaresi ◽  
Lisa Saalbach ◽  
Stuart W. Crane ◽  
Martin J. Paterson ◽  
...  
Keyword(s):  
Excited State ◽  
Angular Distributions ◽  
Relaxation Dynamics ◽  
Photoelectron Imaging ◽  
Time Resolved ◽  
Valence States ◽  
Ultimate Fate ◽  
Site Selective ◽  
Photoelectron Angular Distributions ◽  
Electronic Character

We present results from a recent time-resolved photoelectron imaging (TRPEI) study investigating the non-adiabatic relaxation dynamics of N,N-dimethylaniline (N,N-DMA) and 3,5-dimethylaniline (3,5-DMA) following excitation at 240 nm. Analysis of the experimental data is supported by ab initio coupled-cluster calculations evaluating excited state energies and the evolution of several excited state physical properties as a function of N–H/N–CH3 bond extension – a critical reaction coordinate. The use of site-selective methylation brings considerable new insight to the existing body of literature concerning photochemical dynamics in the related system aniline at similar excitation wavelengths. The present work also builds on our own previous investigations in the same species at 250 nm. The TRPEI method provides highly differential energy- and angle-resolved data and, in particular, the temporal evolution of the photoelectron angular distributions afforded by the imaging approach offers much of the new dynamical information. In particular, we see no clear evidence of the second excited 2ππ* state non-adiabatically coupling to the lower-lying S1(ππ*) state or the mixed Rydberg/valence S2(3s/πσ*) state. This, in turn, potentially raises some unresolved questions about the overall nature of the dynamics operating in these systems, especially in regard to the 2ππ* state's ultimate fate. More generally, the findings for the aromatic systems N,N-DMA and 3,5-DMA, taken along with our recent TRPEI results for several aliphatic amine species, highlight interesting questions about the nature of electronic character evolution in mixed Rydberg-valence states as a function of certain key bond extensions and the extent of system conjugation. We begin exploring these ideas computationally for a systematically varied series of tertiary amines.

Magnetic Dichroism in Resonant Photoemission and Photoabsorption from Gd Metal

1997 ◽  
Vol 475 ◽  
Author(s):  
K. Starke ◽  
G. Van Der Laan ◽  
Z. Hu ◽  
E. Arenholz ◽  
E. Navas ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Giant Resonance ◽  
High Surface ◽  
Magnetic Systems ◽  
X Ray ◽  
Resonant Photoemission ◽  
Excitation Region ◽  
Magnetic Dichroism ◽  
Consistent Picture ◽  
X Ray Absorption

ABSTRACTWe report on the study of MCD in resonant PE, using Gd metal as an example. When the photon energy is changed across the Gd 4d → 4ƒ excitation region, the PE-MCD spectrum varies substantially. Based on atomic-multiplet theory, we present a consistent picture of MCD in resonant 4d → 4ƒ PE and x-ray absorption at the 4d-edge, where all spectral changes can be explained by the angular-momentum of the intermediate absorption state. The present analysis shows: when tuning to a specific line of the 4d x-ray absorption spectrum with a total angular momentum J', only the associate multiplet component is found to resonate. At the ‘giant resonance’, the shape of the MCD-PE signal closely resembles the off-resonance case; this finding is explained within atomic-multiplet theory allowing a straightforward use of MCD in 4d-resonant PE (i) for element-specific analysis of multicomponent magnetic systems with high surface sensitivity and (ii) for surface-domain imaging by PE microscopy.

scholarly journals High-temperature superconductivity and its robustness against magnetic polarization in monolayer FeSe on EuTiO3

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Chong Liu ◽  
Hyungki Shin ◽  
Andrin Doll ◽  
Hsiang-Hsi Kung ◽  
Ryan P. Day ◽  
...  
Keyword(s):  
Spin Polarization ◽  
High Temperature Superconductivity ◽  
Photoemission Spectroscopy ◽  
Antiferromagnetic Order ◽  
Unconventional Superconductivity ◽  
X Ray ◽  
Nematic Ordering ◽  
Magnetic Dichroism ◽  
Close Proximity ◽  
Enhanced Superconductivity

AbstractSpin degree of freedom generally plays an important role in unconventional superconductivity. In many of the iron-based compounds, superconductivity is found in close proximity to long-range antiferromagnetic order, whereas monolayer FeSe grown on SrTiO3, with enhanced superconductivity, exhibits no magnetic or nematic ordering. Here we grow monolayer and multilayer FeSe on antiferromagnetic EuTiO3(001) layers, in an effort to introduce a spin polarization in proximity to the superconductivity of FeSe. By X-ray magnetic dichroism, we observe an antiferromagnet–ferromagnet switching on Eu and Ti sites in EuTiO3 driven by the applied magnetic field, with no concomitant spin polarization on the Fe site of FeSe. Transport measurements show enhanced superconductivity of monolayer FeSe on EuTiO3 with a transition temperature of ~30 K. The band structure revealed by photoemission spectroscopy is analogous to that of FeSe/SrTiO3. Our work creates a platform for the interplay of spin and unconventional superconductivity in the two-dimensional limit.

Sign in / Sign up

Export Citation Format

Share Document