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The c-axis reflectivity spectrum of underdoped YBa2Cu3O6.6 (YBCO) is measured below T(c)=59 K in parallel magnetic fields H parallel CuO2 up to 7 T. Upon application of a parallel field, a new peak appears at finite frequency in the optical conductivity at the expense of suppression of c-axis condensate weight. We conclude that the dramatic change originates from different Josephson coupling strengths between bilayers with and without Josephson vortices. We find that the 400 cm(-1) broad conductivity peak in YBCO gains the spectral weight under parallel magnetic field; this indicates that the condensate weight at omega=0 is distributed to this peak as well as to the new optical Josephson mode. 相似文献
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Fukaya A Fudamoto Y Gat IM Ito T Larkin MI Savici AT Uemura YJ Kyriakou PP Luke GM Rovers MT Kojima KM Keren A Hanawa M Hiroi Z 《Physical review letters》2003,91(20):207603
Muon spin relaxation and magnetic susceptibility measurements have been performed on the pure and diluted spin 1/2 kagomé system (CuxZn(1-x))3V2O7(OH)2 2H2O. In the pure x=1 system we found a slowing down of Cu spin fluctuations with decreasing temperature towards T approximately 1 K, followed by slow and nearly temperature-independent spin fluctuations persisting down to T=50 mK, indicative of quantum fluctuations. No indication of static spin freezing was detected in either of the pure (x=1.0) or diluted samples. The observed magnitude of fluctuating fields indicates that the slow spin fluctuations represent an intrinsic property of kagomé network rather than impurity spins. 相似文献
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Larkin MI Fudamoto Y Gat IM Kinkhabwala A Kojima KM Luke GM Merrin J Nachumi B Uemura YJ Azuma M Saito T Takano M 《Physical review letters》2000,84(9):1982-1985
The two-dimensional electron gas (2DEG) in moderate magnetic fields in ultraclean AlAs-GaAs heterojunctions exhibits transport anomalies suggestive of a compressible anisotropic metallic state. Using scaling arguments and Monte Carlo simulations, we develop an order parameter theory of an electron nematic phase. The observed temperature dependence of the resistivity anisotropy behaves like the orientational order parameter if the transition to the nematic state occurs at a finite temperature T(c) approximately 65 mK, and is slightly rounded by a small background microscopic anisotropy. We propose a light scattering experiment to measure the critical susceptibility. 相似文献
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Kikuchi H. Nagasawa H. Mekata M. Fudamoto Y. Kojima K.M. Luke G.M. Uemura Y.J. Mamiya H. Naka T. 《Hyperfine Interactions》1999,120(1-8):623-627
AgNiO2, a model compound of an S=1/2 triangular lattice, was studied by muon spin relaxation in addition to ac, dc susceptibility,
electrical resistivity and neutron diffraction. The relaxation rate shows a sharp peak at around TN=28 K followed by a sudden decrease of initial asymmetry indicating a magnetic ordering. Three internal fields ranging from
0.2 to 0.3 T were obtained from the muon precession period. However, a neutron diffraction experiment failed to detect any
magnetic order at low temperatures. From these results, it was concluded that magnetic coherence is confined to small domain
compared with the coherence length of neutron diffraction due to spin frustration.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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