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Title: Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu 2 Ir 2 O 7 [Evolution of Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu 2 Ir 2 O 7 ]

Here, we report a resonant inelastic x-ray scattering study of the magnetic excitation spectrum in a highly insulating Eu 2Ir 2O 7 single crystal that exhibits a metal-insulator transition at T MI = 111(7) K. A propagating magnon mode with a 20 meV bandwidth and a 28 meV magnon gap is found in the excitation spectrum at 7 K, which is expected in the all-in-all-out magnetically ordered state. This magnetic excitation exhibits substantial softening as the temperature is raised towards T MI and turns into a highly damped excitation in the paramagnetic phase. Remarkably, the softening occurs throughout the whole Brillouin zone including the zone boundary. This observation is inconsistent with the magnon renormalization expected in a local moment system and indicates that the strength of the electron correlation in Eu 2Ir 2O 7 is only moderate, so that electron itinerancy should be taken into account in describing its magnetism.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [4] ;  [4] ;  [1]
  1. Univ. of Toronto, Toronto, ON (Canada)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Canadian Light Source, Saskatoon, SK (Canada)
  4. Univ. of Tokyo, Kashiwa (Japan)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 120; Journal Issue: 17; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Natural Sciences and Engineering Research Council of Canada (NSERC); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS
OSTI Identifier:
1461517
Alternate Identifier(s):
OSTI ID: 1434977

Chun, Sae Hwan, Yuan, Bo, Casa, Diego, Kim, Jungho, Kim, Chang -Yong, Tian, Zhaoming, Qiu, Yang, Nakatsuji, Satoru, and Kim, Young -June. Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu2Ir2O7 [Evolution of Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu2Ir2O7]. United States: N. p., Web. doi:10.1103/PhysRevLett.120.177203.
Chun, Sae Hwan, Yuan, Bo, Casa, Diego, Kim, Jungho, Kim, Chang -Yong, Tian, Zhaoming, Qiu, Yang, Nakatsuji, Satoru, & Kim, Young -June. Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu2Ir2O7 [Evolution of Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu2Ir2O7]. United States. doi:10.1103/PhysRevLett.120.177203.
Chun, Sae Hwan, Yuan, Bo, Casa, Diego, Kim, Jungho, Kim, Chang -Yong, Tian, Zhaoming, Qiu, Yang, Nakatsuji, Satoru, and Kim, Young -June. 2018. "Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu2Ir2O7 [Evolution of Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu2Ir2O7]". United States. doi:10.1103/PhysRevLett.120.177203.
@article{osti_1461517,
title = {Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu2Ir2O7 [Evolution of Magnetic Excitations across the Metal-Insulator Transition in the Pyrochlore Iridate Eu2Ir2O7]},
author = {Chun, Sae Hwan and Yuan, Bo and Casa, Diego and Kim, Jungho and Kim, Chang -Yong and Tian, Zhaoming and Qiu, Yang and Nakatsuji, Satoru and Kim, Young -June},
abstractNote = {Here, we report a resonant inelastic x-ray scattering study of the magnetic excitation spectrum in a highly insulating Eu2Ir2O7 single crystal that exhibits a metal-insulator transition at TMI = 111(7) K. A propagating magnon mode with a 20 meV bandwidth and a 28 meV magnon gap is found in the excitation spectrum at 7 K, which is expected in the all-in-all-out magnetically ordered state. This magnetic excitation exhibits substantial softening as the temperature is raised towards TMI and turns into a highly damped excitation in the paramagnetic phase. Remarkably, the softening occurs throughout the whole Brillouin zone including the zone boundary. This observation is inconsistent with the magnon renormalization expected in a local moment system and indicates that the strength of the electron correlation in Eu2Ir2O7 is only moderate, so that electron itinerancy should be taken into account in describing its magnetism.},
doi = {10.1103/PhysRevLett.120.177203},
journal = {Physical Review Letters},
number = 17,
volume = 120,
place = {United States},
year = {2018},
month = {4}
}