Superconducting and normal-state properties of single-crystalline Tl0.47Rb0.34Fe1.63Se2 as seen via 77Se and 87Rb NMR

Long Ma; G. F. Ji; J. Zhang; J. B. He; D. M. Wang; G. F. Chen; Wei Bao; Weiqiang Yu

doi:10.1103/PhysRevB.83.174510

Superconducting and normal-state properties of single-crystalline Tl_0.47Rb_0.34Fe_1.63Se₂ as seen via ⁷⁷Se and ⁸⁷Rb NMR

Long Ma, G. F. Ji, J. Zhang, J. B. He, D. M. Wang, G. F. Chen, Wei Bao, Weiqiang Yu^*

^*Corresponding author for this work

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

16 Citations (Scopus)

Abstract

We report both ⁷⁷Se and ⁸⁷Rb nuclear magnetic resonance (NMR) studies on Tl_0.47Rb_0.34Fe_1.63Se₂ single-crystalline superconductors (T_c ≈ 32 K). Singlet superconductivity is suggested by a sharp drop of the Knight shift K(T) below T_c , after subtracting the superconducting diamagnetic effect. However, the Hebel-Slichter coherence peak below T_c is not observed in the spin-lattice relaxation rate 1/T₁ , even with a low in-plane NMR field of 2.6 T. Just above T_c , no evidence of low-energy spin fluctuation is found in the spin-lattice relaxation rate on both the ⁷⁷Se and ⁸⁷Rb sites. Upon warming, however, the Knight shifts and the spin-lattice relaxation rates of both nuclei increase substantially with temperature. In particular, the Knight shift is nearly isotropic and follow a function fit of K = a+bT² from T_c up to 300 K. Our observations should put a strong constraint to the theory of magnetism and superconductivity in the recently discovered iron selenide superconductors.

Original language	English
Article number	174510
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	83
Issue number	17
DOIs	https://doi.org/10.1103/PhysRevB.83.174510
Publication status	Published - 1 May 2011
Externally published	Yes

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@article{1fa1493117e34dcb8151a8f161f07982,

title = "Superconducting and normal-state properties of single-crystalline Tl0.47Rb0.34Fe1.63Se2 as seen via 77Se and 87Rb NMR",

abstract = "We report both 77Se and 87Rb nuclear magnetic resonance (NMR) studies on Tl0.47Rb0.34Fe1.63Se2 single-crystalline superconductors (Tc ≈ 32 K). Singlet superconductivity is suggested by a sharp drop of the Knight shift K(T) below Tc , after subtracting the superconducting diamagnetic effect. However, the Hebel-Slichter coherence peak below Tc is not observed in the spin-lattice relaxation rate 1/T1 , even with a low in-plane NMR field of 2.6 T. Just above Tc , no evidence of low-energy spin fluctuation is found in the spin-lattice relaxation rate on both the 77Se and 87Rb sites. Upon warming, however, the Knight shifts and the spin-lattice relaxation rates of both nuclei increase substantially with temperature. In particular, the Knight shift is nearly isotropic and follow a function fit of K = a+bT2 from Tc up to 300 K. Our observations should put a strong constraint to the theory of magnetism and superconductivity in the recently discovered iron selenide superconductors. ",

author = "Long Ma and Ji, {G. F.} and J. Zhang and He, {J. B.} and Wang, {D. M.} and Chen, {G. F.} and Wei Bao and Weiqiang Yu",

year = "2011",

month = may,

day = "1",

doi = "10.1103/PhysRevB.83.174510",

language = "English",

volume = "83",

journal = "Physical Review B - Condensed Matter and Materials Physics",

issn = "1098-0121",

publisher = "American Physical Society",

number = "17",

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TY - JOUR

T1 - Superconducting and normal-state properties of single-crystalline Tl0.47Rb0.34Fe1.63Se2 as seen via 77Se and 87Rb NMR

AU - Ma, Long

AU - Ji, G. F.

AU - Zhang, J.

AU - He, J. B.

AU - Wang, D. M.

AU - Chen, G. F.

AU - Bao, Wei

AU - Yu, Weiqiang

PY - 2011/5/1

Y1 - 2011/5/1

N2 - We report both 77Se and 87Rb nuclear magnetic resonance (NMR) studies on Tl0.47Rb0.34Fe1.63Se2 single-crystalline superconductors (Tc ≈ 32 K). Singlet superconductivity is suggested by a sharp drop of the Knight shift K(T) below Tc , after subtracting the superconducting diamagnetic effect. However, the Hebel-Slichter coherence peak below Tc is not observed in the spin-lattice relaxation rate 1/T1 , even with a low in-plane NMR field of 2.6 T. Just above Tc , no evidence of low-energy spin fluctuation is found in the spin-lattice relaxation rate on both the 77Se and 87Rb sites. Upon warming, however, the Knight shifts and the spin-lattice relaxation rates of both nuclei increase substantially with temperature. In particular, the Knight shift is nearly isotropic and follow a function fit of K = a+bT2 from Tc up to 300 K. Our observations should put a strong constraint to the theory of magnetism and superconductivity in the recently discovered iron selenide superconductors.

AB - We report both 77Se and 87Rb nuclear magnetic resonance (NMR) studies on Tl0.47Rb0.34Fe1.63Se2 single-crystalline superconductors (Tc ≈ 32 K). Singlet superconductivity is suggested by a sharp drop of the Knight shift K(T) below Tc , after subtracting the superconducting diamagnetic effect. However, the Hebel-Slichter coherence peak below Tc is not observed in the spin-lattice relaxation rate 1/T1 , even with a low in-plane NMR field of 2.6 T. Just above Tc , no evidence of low-energy spin fluctuation is found in the spin-lattice relaxation rate on both the 77Se and 87Rb sites. Upon warming, however, the Knight shifts and the spin-lattice relaxation rates of both nuclei increase substantially with temperature. In particular, the Knight shift is nearly isotropic and follow a function fit of K = a+bT2 from Tc up to 300 K. Our observations should put a strong constraint to the theory of magnetism and superconductivity in the recently discovered iron selenide superconductors.

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U2 - 10.1103/PhysRevB.83.174510

DO - 10.1103/PhysRevB.83.174510

M3 - RGC 21 - Publication in refereed journal

SN - 1098-0121

VL - 83

JO - Physical Review B - Condensed Matter and Materials Physics

JF - Physical Review B - Condensed Matter and Materials Physics

IS - 17

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ER -