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Title: New type of quantum criticality in the pyrochlore iridates

Magnetic fluctuations and electrons couple in intriguing ways in the vicinity of zero-temperature phase transitions—quantum critical points—in conducting materials. Quantum criticality is implicated in non-Fermi liquid behavior of diverse materials and in the formation of unconventional superconductors. Here, we uncover an entirely new type of quantum critical point describing the onset of antiferromagnetism in a nodal semimetal engendered by the combination of strong spin-orbit coupling and electron correlations, and which is predicted to occur in the iridium oxide pyrochlores. We formulate and solve a field theory for this quantum critical point by renormalization group techniques and show that electrons and antiferromagnetic fluctuations are strongly coupled and that both these excitations are modified in an essential way. This quantum critical point has many novel features, including strong emergent spatial anisotropy, a vital role for Coulomb interactions, and highly unconventional critical exponents. Our theory motivates and informs experiments on pyrochlore iridates and constitutes a singular realistic example of a nontrivial quantum critical point with gapless fermions in three dimensions.
Authors:
 [1] ;  [1] ;  [1]
  1. Univ. of California, Santa Barbara, CA (United States)
Publication Date:
Grant/Contract Number:
FG02-08ER46524
Type:
Published Article
Journal Name:
Physical Review. X
Additional Journal Information:
Journal Volume: 4; Journal Issue: 4; Journal ID: ISSN 2160-3308
Publisher:
American Physical Society
Research Org:
Univ. of California, Santa Barbara, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
OSTI Identifier:
1180837
Alternate Identifier(s):
OSTI ID: 1214712