8,824 research outputs found
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
^{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.
Interplay between different states in heavy fermion physics
Calorimetry experiments under high pressure were used to clarify the
interplay between different states such as superconductivity and
antiferromagnetism in CeRhIn5, spin density wave and large moment
antiferromagnetism in URu2Si2. Evidences are given on the re-entrance of
antiferromagnetism under magnetic field in the superconducting phase of CeRhIn5
up to pc = 2.5 GPa where the Neel temperature will collapse in the absence of
superconductivity. For URu2Si2 measurements up to 10 GPa support strongly the
coexistence of spin density wave and large moment antiferromagnetism at high
pressures.Comment: 6 pages, 9 figures, presented at ICM200
New Superconducting and Magnetic Phases Emerge on the Verge of Antiferromagnetism in CeIn
We report the discovery of new superconducting and novel magnetic phases in
CeIn on the verge of antiferromagnetism (AFM) under pressure () through
the In-nuclear quadrupole resonance (NQR) measurements. We have found a
-induced phase separation of AFM and paramagnetism (PM) without any trace
for a quantum phase transition in CeIn. A new type of superconductivity
(SC) was found in GPa to coexist with AFM that is magnetically
separated from PM where the heavy fermion SC takes place. We propose that the
magnetic excitations such as spin-density fluctuations induced by the
first-order magnetic phase transition might mediate attractive interaction to
form Cooper pairs.Comment: 4 pages, 4 EPS figures, submitted to J. Phys. Soc. Jp
Evolution of ferromagnetic circular dichroism coincident with magnetization and anomalous Hall effect in Co-doped rutile TiO2
Magnetic circular dichroism (MCD) of rutile Ti1-xCoxO2-d is systematically
examined with various x and d to reveal a phase diagram for the appearance of
ferromagnetism at higher carrier concentration and Co content. The phase
diagram exactly matches with that determined from anomalous Hall effect (AHE).
The magnetic field dependence of MCD also shows good coincidence with those of
the magnetization and AHE. The coincidence of these independent measurements
strongly suggests single and intrinsic ferromagnetic origin.Comment: 9 pages, 4 figure
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