1,017 research outputs found
Strong Coupling between Antiferromagnetic and Superconducting Order Parameters in CeRhIn Studied by In-NQR Spectroscopy
We report on a novel pressure ()-induced evolution of magnetism and
superconductivity (SC) in a helical magnet CeRhIn with an incommensurate
wave vector through the In nuclear quadrupole
resonance (NQR) measurements under . Systematic measurements of the
In-NQR spectrum reveal that the commensurate antiferromagnetism (AFM)
with is realized above 1.7 GPa. An
important finding is that the size of SC gap and increase as the
magnitude of the AFM moment decreases in the region, where SC uniformly
coexists with the commensurate AFM. This result provides evidence of strong
coupling between the commensurate AFM order parameter (OP) and SC OP.Comment: 5 pages, 5 figure
Gapless Magnetic and Quasiparticle Excitations due to the Coexistence of Antiferromagnetism and Superconductivity in CeRhIn : A study of In-NQR under Pressure
We report systematic measurements of ac-susceptibility,
nuclear-quadrupole-resonance spectrum, and nuclear-spin-lattice-relaxation time
() on the pressure ()- induced heavy-fermion (HF) superconductor
CeRhIn. The temperature () dependence of at = 1.6 GPa has
revealed that antiferromagnetism (AFM) and superconductivity (SC) coexist
microscopically, exhibiting the respective transition at K and
= 0.9 K. It is demonstrated that SC does not yield any trace of gap
opening in low-lying excitations below K, but K, followed by a = const law. These results point to the
unconventional characteristics of SC coexisting with AFM. We highlight that
both of the results deserve theoretical work on the gapless nature in low-lying
excitation spectrum due to the coexistence of AFM and SC and the lack of the
mean-field regime below K.Comment: 4pages,5figures,revised versio
Novel phase diagram for antiferromagnetism and superconductivity in pressure-induced heavy-fermion superconductor CeRhIn probed by In-NQR
We present a novel phase diagram for the antiferromagnetism and
superconductivity in CeRhIn probed by In-NQR studies under pressure
(). The quasi-2D character of antiferromagnetic spin fluctuations in the
paramagnetic state at = 0 evolves into a 3D character because of the
suppression of antiferromagnetic order for 1.36 GPa (QCP:
antiferromagnetic quantum critical point). Nuclear-spin-lattice-relaxation rate
measurements revealed that the superconducting order occurs in the
range 1.36 -- 1.84 GPa, with maximum 0.9 K around
1.36 GPa.Comment: 5 pages, 5 figures, submitted to PR
Density of States and NMR Relaxation Rate in Anisotropic Superconductivity with Intersecting Line Nodes
We show that the density of states in an anisotropic superconductor with
intersecting line nodes in the gap function is proportional to for , where is the maximum value of
the gap function and is constant, while it is proportional to if
the line nodes do not intersect. As a result, a logarithmic correction appears
in the temperature dependence of the NMR relaxation rate and the specific heat,
which can be observed experimentally. By comparing with those for the heavy
fermion superconductors, we can obtain information about the symmetry of the
gap function.Comment: 7 pages, 4 PostScript Figures, LaTeX, to appear in J. Phys. Soc. Jp
^{115}In-NQR evidence for unconventional superconductivity in CeIn_3 under pressure
We report evidence for unconventional superconductivity in CeIn_3 at a
pressure P = 2.65 GPa above critical pressure (P_c ~ 2.5 GPa) revealed by the
measurements of nuclear-spin-lattice-relaxation time (T_1) and
ac-susceptibility (ac-chi). Both the measurements of T_1 and ac-chi have
pointed to a superconducting transition at T_c = 95 mK, which is much lower
than an onset temperature T_{onset} = 0.15 K at zero resistance. The
temperature dependence of 1/T_1 shows no coherence peak just below T_c,
indicative of an unconventional nature for the superconductivity induced in
CeIn_3.Comment: 4 pages, 4 figures, to be published in Phys.Rev.
Emergent Phases of Nodeless and Nodal Superconductivity Separated by Antiferromagnetic Order in Iron-based Superconductor (Ca4Al2O6)Fe2(As1-xPx)2: 75As- and 31P-NMR Studies
We report P- and As-NMR studies on
(CaAlO)Fe(AsP) with an isovalent substitution
of P for As. We present the novel evolution of emergent phases that the
nodeless superconductivity (SC) in 00.4 and the nodal one around
=1 are intimately separated by the onset of a commensurate stripe-type
antiferromagnetic (AFM) order in 0.5 0.95, as an isovalent
substitution of P for As decreases a pnictogen height measured from
the Fe plane. It is demonstrated that the AFM order takes place under a
condition of 1.32\AA1.42\AA, which is also the case for other
Fe-pnictides with the Fe state in (Fe) layers. This novel
phase evolution with the variation in points to the importance of
electron correlation for the emergence of SC as well as AFM order.Comment: 5pages, 4figures; accepted for publication as a Rapid Communication
in Phys. Rev.
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