Browsing by Author "Young, B. -L."

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Coexistence of antiferromagnetism and superconductivity in CeCo(In0.9Cd0.1)(5): A spin lattice relaxation study
(2008-04-01)
Urbano, R. R.
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Young, B. -L.
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Curro, N. J.
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Thompson, J. D.
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Pham, L. D.
We present an In(1) NQR study on the heavy-fermion (HF) compound CeCo(In1-xCdx)(5) (x = 0.10). Bulk measurements indicate that Cd doping acts as an electronic tuning agent in CeCoIn5, and that superconductivity (SC) and antiferromagnetism (AFM) may coexist at ambient pressure for 0.05 < x < 0.15. For x = 0.10, the nuclear spin lattice relaxation rate shows a broad peak at the Neel temperature T-N = 2.8 K, with a subsequent onset of SC at T-c similar or equal to 1.2 K. Our results provide strong evidence for microscopic coexistence of these two ground states. The nuclear magnetization recovery curves in both the ordered and mixed states reveal a single T-i-component, which suggests a homogeneous nature of the Ce-4f(1) electronic state. (c) 2007 Elsevier B.V. All rights reserved.
Magnetoelectric effect induced by the delocalised Nb-93m state
(2015-01-02)
Cheng, Y.
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Guo, Z. -Y.
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Liu, Y. -L.
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Young, B. -L.
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Lee, C. -H.
We herein report on the density- and temperature-dependent decay of the Nb-93m nuclear excited atom and present a simple interpretation of the underlying physics. This anomaly indicates nuclear resonant absorption and delocalisation of the long-lived Mossbauer state in the crystal. A non-linear magnetoelectric response, on low-frequency drive current, appeared in the bulk metal of a high-purity niobium crystal and then disappeared along with the disappearance of delocalised nuclear excitation. Several non-linear resonant peaks, of the order of several hundred Hertz, increased in magnitude with the applied magnetic field, and the central frequencies of these peaks decreased with temperature.
Microscopic evidence for field-induced magnetism in CeCoIn5
(2007-01-19)
Young, B. -L.
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Urbano, R. R.
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Curro, N. J.
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Thompson, J. D.
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Sarrao, J. L.
We present NMR data in the normal and superconducting states of CeCoIn5 for fields close to H-c2(0)=11.8 T in the ab plane. Recent experiments identified a first-order transition from the normal to superconducting state for H > 10.5 T, and a new thermodynamic phase below 290 mK within the superconducting state. We find that the Knight shifts of the In(1), In(2), and the Co are discontinuous across the first-order transition and the magnetic linewidths increase dramatically. The broadening differs for the three sites, unlike the expectation for an Abrikosov vortex lattice, and suggests the presence of static spin moments in the vortex cores. In the low-temperature and high-field phase, the broad NMR lineshapes suggest ordered local moments, rather than a long-wavelength quasiparticle spin density modulation expected for an FFLO phase.
Probing the magnetism in the CeMIn5 heavy fermion systems by NMR
(2008-04-01)
Curro, N. J.
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Urbano, R. R.
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Young, B. -L.
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電子物理學系
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Department of Electrophysics
The CeMIn5 heavy fermion system exhibits antiferromagnetism for both M = Rh and M = Co. CeRhIn5 is antiferromagnetic at ambient pressure and superconducting under hydrostatic pressure, whereas CeCoIn5 is superconducting at ambient pressure, but becomes antiferromagnetic with substitution of In by a few percent of Cd. Pure CeCoIn5 exhibits a field-induced magnetic phase that coexists with the superconductivity. Nuclear magnetic resonance (NMR) and nuclear quadrupolar resonance (NQR) studies of the In(1), In(2) and Co sites reveal similar features in the magnetic states of these systems. (c) 2007 Published by Elsevier B.V.