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Title: Localized-itinerant dichotomy and unconventional magnetism in SrRu2O6

Abstract

Electron correlations tend to generate local magnetic moments that usually order if the lattices are not too frustrated. The hexagonal compound SrRu$$_2$$O$$_6$$ has a relatively high N{\'e}el temperature but small local moments, which seem to be at odds with the nominal valence of Ru$$^{5+}$$ in the $$t_{2g}^3$$ configuration. Here, we investigate the electronic and magnetic properties of SrRu$$_2$$O$$_6$$ using density functional theory (DFT) combined with dynamical mean field theory (DMFT). We find that the strong hybridization between Ru $d$ and O $p$ states results in a Ru valence that is closer to $+4$, leading to the small ordered moment, consistent with a DFT prediction. While the agreement with DFT might indicate that SrRu$$_2$$O$$_6$$ is in the weak coupling regime, our DMFT studies provide evidence from the mass enhancement and local moment formation that indicate correlation effects play a significant role. The local moment per Ru site is about a factor 2 larger than the ordered moment at low temperatures and remains finite in the whole temperature range investigated. Our theoretical N{\'e}el temperature $$\sim 700$$~K is in reasonable agreement with experimental observations. Due to a small lattice distortion, the degenerate $$t_{2g}$$ manifold is split and the quasiparticle weight is renormalized significantly in the $$a_{1g}$$ state, while correlation effects in $$e_g'$$ states are about a factor of 2--3 weaker. SrRu$$_2$$O$$_6$$ is a unique system in which localized and itinerant electrons coexist with the proximity to an orbitally-selective Mott transition within the $$t_{2g}$$ sector.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1394320
DOE Contract Number:
AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Scientific Reports; Journal Volume: 7; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Okamoto, Satoshi, Ochi, Masayuki, Arita, Ryotaro, Yan, Jiaqiang, and Trivedi, Nandini. Localized-itinerant dichotomy and unconventional magnetism in SrRu2O6. United States: N. p., 2017. Web. doi:10.1038/s41598-017-08503-y.
Okamoto, Satoshi, Ochi, Masayuki, Arita, Ryotaro, Yan, Jiaqiang, & Trivedi, Nandini. Localized-itinerant dichotomy and unconventional magnetism in SrRu2O6. United States. doi:10.1038/s41598-017-08503-y.
Okamoto, Satoshi, Ochi, Masayuki, Arita, Ryotaro, Yan, Jiaqiang, and Trivedi, Nandini. 2017. "Localized-itinerant dichotomy and unconventional magnetism in SrRu2O6". United States. doi:10.1038/s41598-017-08503-y.
@article{osti_1394320,
title = {Localized-itinerant dichotomy and unconventional magnetism in SrRu2O6},
author = {Okamoto, Satoshi and Ochi, Masayuki and Arita, Ryotaro and Yan, Jiaqiang and Trivedi, Nandini},
abstractNote = {Electron correlations tend to generate local magnetic moments that usually order if the lattices are not too frustrated. The hexagonal compound SrRu$_2$O$_6$ has a relatively high N{\'e}el temperature but small local moments, which seem to be at odds with the nominal valence of Ru$^{5+}$ in the $t_{2g}^3$ configuration. Here, we investigate the electronic and magnetic properties of SrRu$_2$O$_6$ using density functional theory (DFT) combined with dynamical mean field theory (DMFT). We find that the strong hybridization between Ru $d$ and O $p$ states results in a Ru valence that is closer to $+4$, leading to the small ordered moment, consistent with a DFT prediction. While the agreement with DFT might indicate that SrRu$_2$O$_6$ is in the weak coupling regime, our DMFT studies provide evidence from the mass enhancement and local moment formation that indicate correlation effects play a significant role. The local moment per Ru site is about a factor 2 larger than the ordered moment at low temperatures and remains finite in the whole temperature range investigated. Our theoretical N{\'e}el temperature $\sim 700$~K is in reasonable agreement with experimental observations. Due to a small lattice distortion, the degenerate $t_{2g}$ manifold is split and the quasiparticle weight is renormalized significantly in the $a_{1g}$ state, while correlation effects in $e_g'$ states are about a factor of 2--3 weaker. SrRu$_2$O$_6$ is a unique system in which localized and itinerant electrons coexist with the proximity to an orbitally-selective Mott transition within the $t_{2g}$ sector.},
doi = {10.1038/s41598-017-08503-y},
journal = {Scientific Reports},
number = 1,
volume = 7,
place = {United States},
year = 2017,
month = 9
}
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