Physica B: Condensed Matter
Volume 261, Issue 1, 01-January-1999
Physica B: Condensed Matter Vol. 261 (1) p. 588
Copyright (c) 1999 All rights reserved.
Nature of the spin state in TmNi2B2C
R. Nagarajana, E. Allenob, S.J. Blundellc,
Chandan Mazumdara, D.W. Cooked, S.P.
Cottrelle, S.F.J. Coxe, C. Godartb,
L.C. Guptaa, Z. Hossaina, W.L. Hultsd,
Th. Jestadtc, E.J. Petersond, F.L.
Prattc, J.L. Smithd
aSolid State Physics Group, Tata Institute of Fundamental
Research, Homi Bhabha Road, Colaba, , Mumbai 400 005, India
bUPR-209, C.N.R.S., Groupe des Laboratoires de Thiais,
F 94320 Thiais, , , France
cClarendon Laboratory, , Oxford, OX1 3PU, UK
dL.A.N.L., Los Alamos, , NM 87545, USA
eISIS, R.A.L., , Oxon, OX11 0QX, UK
Abstract
We had observed earlier that in the quaternary borocarbide magnetic superconductor
TmNi2B2C (
Tc=11 K, TN=1.5
K) quasistatic magnetic correlations persist well above TN
(up to ~20 K), which is rather unusual. To further probe the
nature of its spin state, we used magnetically oriented powder samples
of TmNi2B2C and the µ-SR technique. We observe
that the quasistatic internal field has a well defined direction. The spontaneous
muon precession signal has three times the amplitude when the c
-axis
alignment is perpendicular to the initial muon beam polarization than when
parallel. The transverse configuration enhances the oscillatory signal.
This has enabled us to show that the quasistatic magnetic correlations
persist even up to 50 K. Furthermore, we find a peak around 7 G in the
field dependence of the longitudinal relaxation, which we attribute to
the presence of a level crossing resonance arising from quadrupole levels
of the boron nuclei.
Keyword(s): Quaternary borocarbides; Coexistence of superconductivity
and magnetism; µ-SR; TmNi2B2C
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Thomas Jestädt, 1999.
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