The Pseudogap in La(2-x)Sr(x)CuO(4): A Raman Viewpoint

We report the results of Raman scattering experiments on single crystals of La(2-x)Sr(x)CuO(4) [La214] as a function of temperature and doping. In underdoped compounds low-energy B1g spectral weight is depleted in association with the opening of a pseudogap on regions of the Fermi surface located near (pi, 0) and (0, pi). The magnitude of the depletion increases with decreasing doping, and in the most underdoped samples, with decreasing temperature. The spectral weight that is lost at low-energies (omega < 800 cm-1) is transferred to the higher energy region normally occupied by multi-magnon scattering. From the normal state B2g spectra we have determined the scattering rate Gamma(omega, T) of qausiparticles located near the diagonal directions in k-space, (pi/2, pi/2) regions. In underdoped compounds, Gamma(omega, T) is suppressed at low temperatures for energies less than Eg(x) ~ 800 cm-1. The observed doping dependence of the two-magnon scattering and the scattering rate suppression thus suggest that the pseudogap is characterized by an energy scale Eg ~ J, where J is the antiferromagnetic super-exchange energy. Comparison with the results from other techniques provides a consistent picture of the pseudogap in La214.Comment: 6 pages, 5 figures, minor revisions include correct form of the B2g Raman response function and new figures of the recalculated B2g scattering rate. Presented at the APS March99 Meeting, accepted for publication in the Canadian Journal of Physic

Theory of standing spin waves in finite-size chiral spin soliton lattice

We present a theory of standing spin wave (SSW) in a monoaxial chiral helimagnet. Motivated by experimental findings on the magnetic field-dependence of the resonance frequency in thin films of Cr${}$Nb$_{3}$S${}_{6}$[Goncalves et al., Phys. Rev. B95, 104415 (2017)], we examine the SSW over a chiral soliton lattice (CSL) excited by an ac magnetic field applied parallel and perpendicular to the chiral axis. For this purpose, we generalize Kittel-Pincus theories of the SSW in ferromagnetic thin films to the case of non-collinear helimagnet with the surface end spins which are softly pinned by an anisotropy field. Consequently, we found there appear two types of modes. One is a Pincus mode which is composed of a long-period Bloch wave and a short-period ripple originated from the periodic structure of the CSL. Another is a short-period Kittel ripple excited by space-periodic perturbation which exists only in the case where the ac field is applied perpendicular the chiral axis. We demonstrate that the existence of the Pincus mode and the Kittel ripple is consistent with experimentally found double resonance profile.Comment: 17 pages, 14 figure

Laser-Induced Skyrmion Writing and Erasing in an Ultrafast Cryo-Lorentz Transmission Electron Microscopy

We demonstrate that light-induced heat pulses of different duration and energy can write skyrmions in a broad range of temperatures and magnetic field in FeGe. Using a combination of camera-rate and pump-probe cryo-Lorentz Transmission Electron Microscopy, we directly resolve the spatio-temporal evolution of the magnetization ensuing optical excitation. The skyrmion lattice was found to maintain its structural properties during the laser-induced demagnetization, and its recovery to the initial state happened in the sub-{\mu}s to {\mu}s range, depending on the cooling rate of the system

Experimental Signature of Medium Modifications for rho and omega Mesons in the 12 GeV p + A Reactions

The invariant mass spectra of e+e- pairs produced in 12-GeV proton-induced nuclear reactions are measured at the KEK Proton-Synchrotron. On the low-mass side of the omega meson peak, a significant enhancement over the known hadronic sources has been observed. The mass spectra, including the excess, are well reproduced by a model that takes into account the density dependence of the vector meson mass modification, as theoretically predicted.Comment: 4 pages, 3 figures, Version accepted for Physical Review Lette

Response to: Hypoglossal Nerve Unjury after Cervical Spine Surgery

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licens

Direct observation of the washboard noise of a driven vortex lattice in a high-temperature superconductor, Bi2Sr2CaCu2Oy

We studied the conduction noise spectrum in the vortex state of a high-temperature superconductor, Bi2Sr2CaCu2Oy, subject to a uniform driving force. Two characteristic features, a broadband noise (BBN) and a narrow-band noise (NBN), were observed in the vortex-solid phase. The origin of the large BBN was determined to be plastic motion of the vortices, whereas the NBN was found to originate from the washboard modulation of the translational velocity of the driven vortices. We believe this to be the first observation ofComment: 4 pages, 4 figures, to appear in Phys. Rev. Let