Novel Character of Spin Fluctuations in Spin-Triplet Superconductor Sr2RuO4

17O-NMR Study

Hidekazu Mukuda, Kenji Ishida, Yoshio Kitaoka, Kunisuke Asayama, Zhiqiang Mao, Yasumitsu Mori, Yoshiteru Maeno

Research output: Contribution to journalArticle

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Abstract

We report 17O-NMR studies in the normal state of high-quality single-crystal Sr2RuO4 with Tc ∼1.5 K, which has been identified as spin-triplet p-wave superconductor. From systematic measurements of the Knight shift and the nuclear spin-lattice relaxation time T1 on the O(1) sites in the RuO2 planes and the O(2) sites in the SrO layers, microscopic distribution of the spin density on the p Orbitals and the anisotropy of low-frequency components of dynamical susceptibility χ(q, ωn) have been unraveled as follows; (1) The spin susceptibility at the O(1) sites is much larger than that at the O(2) sites. (2) From the anisotropy in the Knight shift at the O(1) sites, it is shown that the spin density resides predominantly on the in-plane pπ orbitals hybridized with the 4dxy orbitals. (3) From the pronounced anisotropy in (1/T1T) at both sites developed below T*∼130K where the c-axis resistivity shows a metallic behavior, we have found that the low-frequency components of χ(q, ωn) is highly anisotropic in contrast to the uniform spin susceptibility being isotropic. The in-plane components of χ(q, ωn) at the O(1) sites are almost independent of wave number although they are exchange-enhanced, whereas its out-of-plane component is markedly enhanced by interlayer antiferromagnetic (AF) spin fluctuations below T* ∼ 130 K. (4) For the apical O(2) sites on which the p orbitals are hybridized with the 4dxz,yz and pc orbitals on the O() site, the in-plane components of χ(q, ωn) are enhanced by AF-spin fluctuations as well. The AF-spin fluctuations develop as quasiparticles hop coherently along the c-axis below T*. These characteristics of spin fluctuations are suggested to provide a new scenario based on the Hund's coupling as a possible mechanism of spin-triplet p-wave superconductivity in Sr2RuO4, not on analogy with 3He.

Original languageEnglish (US)
Pages (from-to)3945-3951
Number of pages7
JournalJournal of the Physical Society of Japan
Volume67
Issue number11
DOIs
StatePublished - Jan 1 1998

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nuclear magnetic resonance
orbitals
magnetic permeability
anisotropy
low frequencies
spin-lattice relaxation
nuclear spin
interlayers
superconductivity
relaxation time
electrical resistivity
single crystals

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Mukuda, Hidekazu ; Ishida, Kenji ; Kitaoka, Yoshio ; Asayama, Kunisuke ; Mao, Zhiqiang ; Mori, Yasumitsu ; Maeno, Yoshiteru. / Novel Character of Spin Fluctuations in Spin-Triplet Superconductor Sr2RuO4 : 17O-NMR Study. In: Journal of the Physical Society of Japan. 1998 ; Vol. 67, No. 11. pp. 3945-3951.
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abstract = "We report 17O-NMR studies in the normal state of high-quality single-crystal Sr2RuO4 with Tc ∼1.5 K, which has been identified as spin-triplet p-wave superconductor. From systematic measurements of the Knight shift and the nuclear spin-lattice relaxation time T1 on the O(1) sites in the RuO2 planes and the O(2) sites in the SrO layers, microscopic distribution of the spin density on the p Orbitals and the anisotropy of low-frequency components of dynamical susceptibility χ(q, ωn) have been unraveled as follows; (1) The spin susceptibility at the O(1) sites is much larger than that at the O(2) sites. (2) From the anisotropy in the Knight shift at the O(1) sites, it is shown that the spin density resides predominantly on the in-plane pπ orbitals hybridized with the 4dxy orbitals. (3) From the pronounced anisotropy in (1/T1T) at both sites developed below T*∼130K where the c-axis resistivity shows a metallic behavior, we have found that the low-frequency components of χ(q, ωn) is highly anisotropic in contrast to the uniform spin susceptibility being isotropic. The in-plane components of χ(q, ωn) at the O(1) sites are almost independent of wave number although they are exchange-enhanced, whereas its out-of-plane component is markedly enhanced by interlayer antiferromagnetic (AF) spin fluctuations below T* ∼ 130 K. (4) For the apical O(2) sites on which the p orbitals are hybridized with the 4dxz,yz and pc orbitals on the O() site, the in-plane components of χ(q, ωn) are enhanced by AF-spin fluctuations as well. The AF-spin fluctuations develop as quasiparticles hop coherently along the c-axis below T*. These characteristics of spin fluctuations are suggested to provide a new scenario based on the Hund's coupling as a possible mechanism of spin-triplet p-wave superconductivity in Sr2RuO4, not on analogy with 3He.",
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Novel Character of Spin Fluctuations in Spin-Triplet Superconductor Sr2RuO4 : 17O-NMR Study. / Mukuda, Hidekazu; Ishida, Kenji; Kitaoka, Yoshio; Asayama, Kunisuke; Mao, Zhiqiang; Mori, Yasumitsu; Maeno, Yoshiteru.

In: Journal of the Physical Society of Japan, Vol. 67, No. 11, 01.01.1998, p. 3945-3951.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Novel Character of Spin Fluctuations in Spin-Triplet Superconductor Sr2RuO4

T2 - 17O-NMR Study

AU - Mukuda, Hidekazu

AU - Ishida, Kenji

AU - Kitaoka, Yoshio

AU - Asayama, Kunisuke

AU - Mao, Zhiqiang

AU - Mori, Yasumitsu

AU - Maeno, Yoshiteru

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N2 - We report 17O-NMR studies in the normal state of high-quality single-crystal Sr2RuO4 with Tc ∼1.5 K, which has been identified as spin-triplet p-wave superconductor. From systematic measurements of the Knight shift and the nuclear spin-lattice relaxation time T1 on the O(1) sites in the RuO2 planes and the O(2) sites in the SrO layers, microscopic distribution of the spin density on the p Orbitals and the anisotropy of low-frequency components of dynamical susceptibility χ(q, ωn) have been unraveled as follows; (1) The spin susceptibility at the O(1) sites is much larger than that at the O(2) sites. (2) From the anisotropy in the Knight shift at the O(1) sites, it is shown that the spin density resides predominantly on the in-plane pπ orbitals hybridized with the 4dxy orbitals. (3) From the pronounced anisotropy in (1/T1T) at both sites developed below T*∼130K where the c-axis resistivity shows a metallic behavior, we have found that the low-frequency components of χ(q, ωn) is highly anisotropic in contrast to the uniform spin susceptibility being isotropic. The in-plane components of χ(q, ωn) at the O(1) sites are almost independent of wave number although they are exchange-enhanced, whereas its out-of-plane component is markedly enhanced by interlayer antiferromagnetic (AF) spin fluctuations below T* ∼ 130 K. (4) For the apical O(2) sites on which the p orbitals are hybridized with the 4dxz,yz and pc orbitals on the O() site, the in-plane components of χ(q, ωn) are enhanced by AF-spin fluctuations as well. The AF-spin fluctuations develop as quasiparticles hop coherently along the c-axis below T*. These characteristics of spin fluctuations are suggested to provide a new scenario based on the Hund's coupling as a possible mechanism of spin-triplet p-wave superconductivity in Sr2RuO4, not on analogy with 3He.

AB - We report 17O-NMR studies in the normal state of high-quality single-crystal Sr2RuO4 with Tc ∼1.5 K, which has been identified as spin-triplet p-wave superconductor. From systematic measurements of the Knight shift and the nuclear spin-lattice relaxation time T1 on the O(1) sites in the RuO2 planes and the O(2) sites in the SrO layers, microscopic distribution of the spin density on the p Orbitals and the anisotropy of low-frequency components of dynamical susceptibility χ(q, ωn) have been unraveled as follows; (1) The spin susceptibility at the O(1) sites is much larger than that at the O(2) sites. (2) From the anisotropy in the Knight shift at the O(1) sites, it is shown that the spin density resides predominantly on the in-plane pπ orbitals hybridized with the 4dxy orbitals. (3) From the pronounced anisotropy in (1/T1T) at both sites developed below T*∼130K where the c-axis resistivity shows a metallic behavior, we have found that the low-frequency components of χ(q, ωn) is highly anisotropic in contrast to the uniform spin susceptibility being isotropic. The in-plane components of χ(q, ωn) at the O(1) sites are almost independent of wave number although they are exchange-enhanced, whereas its out-of-plane component is markedly enhanced by interlayer antiferromagnetic (AF) spin fluctuations below T* ∼ 130 K. (4) For the apical O(2) sites on which the p orbitals are hybridized with the 4dxz,yz and pc orbitals on the O() site, the in-plane components of χ(q, ωn) are enhanced by AF-spin fluctuations as well. The AF-spin fluctuations develop as quasiparticles hop coherently along the c-axis below T*. These characteristics of spin fluctuations are suggested to provide a new scenario based on the Hund's coupling as a possible mechanism of spin-triplet p-wave superconductivity in Sr2RuO4, not on analogy with 3He.

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