Muon spin relaxation studies of incommensurate magnetism and superconductivity in stage-4 La2CuO4.11 and La1.88Sr0.12CuO4. Savici, A. T.; Fudamoto, Y.; Gat, I. M.; Ito, T.; Larkin, M. I.; Uemura, Y. J.; Luke, G. M.; Kojima, K. M.; Lee, Y. S.; Kastner, M. A.; Birgeneau, R. J.; and Yamada, K. Physical Review B, 66(1):014524+, 2002.
Muon spin relaxation studies of incommensurate magnetism and superconductivity in stage-4 La2CuO4.11 and La1.88Sr0.12CuO4 [link]Paper  doi  abstract   bibtex   
We report muon spin relaxation (μSR) measurements using single crystals of oxygen-intercalated stage-4 La2CuO4.11 (LCO:4.11) and La1.88Sr0.12CuO4 (LSCO:0.12), in which neutron scattering studies have found incommensurate magnetic Bragg reflections. In both systems, zero-field μSR measurements show muon spin precession below the Néel temperature TN with frequency 3.6 MHz at T⃗0, having a Bessel function line shape, characteristic of spin-density-wave systems. The amplitude of the oscillating and relaxing signals of these systems is less than half the value expected for systems with static magnetic order in 100% of the volume. Our results are consistent with a simulation of local fields for a heuristic model with (a) incommensurate spin amplitude modulation with the maximum ordered Cu moment size of ∼0.36μB, (b) static Cu moments on the CuO2 planes forming ” islands” having typical radius 15–30 \textbackslashAA, comparable to the in-plane superconducting coherence length, and (c) the measured volume fraction of magnetic muon sites Vμ increasing progressively with decreasing temperature below TN towards Vμ∼40% for LCO:4.11 and 18% for LSCO:0.12 at T⃗0. These results may be compared with correlation lengths in excess of 600 \textbackslashAA and a long range ordered moment of 0.15±0.05μB measured with neutron scattering techniques. In this paper we discuss a model that reconciles these apparently contradictory results. In transverse magnetic field μSR measurements, sensitive to the in-plane magnetic field penetration depth λab, the results for LCO:4.11 and LSCO:0.12 follow correlations found for underdoped, overdoped and Zn-doped high-Tc cuprate systems in a plot of Tc versus the superconducting relaxation rate σ(T⃗0). This indicates that the volume-integrated value of ns/m* (superconducting carrier density / effective mass) is a determining factor for Tc, not only in high-Tc cuprate systems without static magnetism, but also in the present systems where superconductivity coexists with static spin-density-wave spin order.
@article{savici_muon_2002,
	title = {Muon spin relaxation studies of incommensurate magnetism and superconductivity in stage-4 {La}2CuO4.11 and {La}1.88Sr0.12CuO4},
	volume = {66},
	issn = {0163-1829},
	url = {http://dx.doi.org/10.1103/physrevb.66.014524},
	doi = {10.1103/physrevb.66.014524},
	abstract = {We report muon spin relaxation (μSR) measurements using single crystals of oxygen-intercalated stage-4 La2CuO4.11 (LCO:4.11) and La1.88Sr0.12CuO4 (LSCO:0.12), in which neutron scattering studies have found incommensurate magnetic Bragg reflections. In both systems, zero-field μSR measurements show muon spin precession below the Néel temperature TN with frequency 3.6 MHz at T⃗0, having a Bessel function line shape, characteristic of spin-density-wave systems. The amplitude of the oscillating and relaxing signals of these systems is less than half the value expected for systems with static magnetic order in 100\% of the volume. Our results are consistent with a simulation of local fields for a heuristic model with (a) incommensurate spin amplitude modulation with the maximum ordered Cu moment size of ∼0.36μB, (b) static Cu moments on the CuO2 planes forming ” islands” having typical radius 15–30 {\textbackslash}AA, comparable to the in-plane superconducting coherence length, and (c) the measured volume fraction of magnetic muon sites Vμ increasing progressively with decreasing temperature below TN towards Vμ∼40\% for LCO:4.11 and 18\% for LSCO:0.12 at T⃗0. These results may be compared with correlation lengths in excess of 600 {\textbackslash}AA and a long range ordered moment of 0.15±0.05μB measured with neutron scattering techniques. In this paper we discuss a model that reconciles these apparently contradictory results. In transverse magnetic field μSR measurements, sensitive to the in-plane magnetic field penetration depth λab, the results for LCO:4.11 and LSCO:0.12 follow correlations found for underdoped, overdoped and Zn-doped high-Tc cuprate systems in a plot of Tc versus the superconducting relaxation rate σ(T⃗0). This indicates that the volume-integrated value of ns/m* (superconducting carrier density / effective mass) is a determining factor for Tc, not only in high-Tc cuprate systems without static magnetism, but also in the present systems where superconductivity coexists with static spin-density-wave spin order.},
	number = {1},
	journal = {Physical Review B},
	author = {Savici, A. T. and Fudamoto, Y. and Gat, I. M. and Ito, T. and Larkin, M. I. and Uemura, Y. J. and Luke, G. M. and Kojima, K. M. and Lee, Y. S. and Kastner, M. A. and Birgeneau, R. J. and Yamada, K.},
	year = {2002},
	keywords = {citano},
	pages = {014524+}
}
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