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          Institute: MPI für Chemische Physik fester Stoffe     Collection: publications 2002     Display Documents

ID: 17457.0, MPI für Chemische Physik fester Stoffe / publications 2002
Exotic magnetism and superconductivity in Ge-substituted CeCu2Si2: A Cu NQR study
Authors:Kawasaki, Y.; Ishida, K.; Obinata, K.; Tabuchi, K.; Kashima, K.; Kitaoka, Y.; Trovarelli, O.; Geibel, C.; Steglich, F.
Date of Publication (YYYY-MM-DD):2002-12-01
Title of Journal:Physical Review B
Journal Abbrev.:Phys. Rev. B
Issue / Number:22
Start Page:224502
End Page:224502
Sequence Number of Article:224502
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:We report Cu NQR results on Ge-doped heavy-fermion superconductors CeCu2(Si1-xGex)(2) (0< x≦0.2) and compare with previous results on Ce0.99Cu2.02Si2 (x=0). Once only 1% Ge is substituted for Si to expand the lattice, an antiferromagnetic (AFM) order sets in at T-N&SIM;0.7 K, followed by the onset of superconductivity at T-c=0.5 K. The sudden emergence of AFM order due to the slight Ge doping reinforces that an exotic magnetic phase at x=0 is in fact a marginal AFM state where slowly fluctuating AFM waves propagate over a long distance. The appearance of internal fields throughout the sample that is deduced from the NQR spectral shape below T-N, excludes the presence of phase segregation between the superconducting (SC) and the AFM phases in the coexistent state below T-c. The 1/T-1 result does not show significant reduction below T-c, followed by a T1T=const behavior. This indicates that the SC phase is in a gapless regime, dominated by magnetic excitations due to the coexistence of AFM and SC phase. As Ge content increases, T-N is progressively increased, while T-c is steeply decreased. As a result of the suppression of the slowly fluctuating AFM waves in the samples with more than x=0.06, their magnetic properties above T-N progressively change to those in a localized regime as observed in CeCu2Ge2. The exotic interplay between magnetism and superconductivity in 0≦x<0.06 is discussed in the context of a SO(5) theory that unifies superconductivity and antiferromagnetism.
Comment of the Author/Creator:Date: 2002, DEC 1
External Publication Status:published
Document Type:Article
Communicated by:Ina Wanschura
Affiliations:MPI für chemische Physik fester Stoffe
External Affiliations:Univ Tokushima, Fac Engn, Dept Phys, Tokushima 7708506, Japan; Osaka Univ, Grad Sch Engn Sci, Dept Phys Sci, Osaka 5608531, Japan; Max Planck Inst Chem Phys Solids, D-01187 Dresden, Germany
Identifiers:ISI:000180279000067 [ID No:1]
ISSN:1098-0121 [ID No:2]
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