Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
de Haas-van Alphen effect investigations of the electronic structure of pure and aluminum-doped MgB_2  [PDF]
A. Carrington,E. A. Yelland,J. D. Fletcher,J. R. Cooper
Physics , 2006, DOI: 10.1016/j.physc.2007.01.027
Abstract: Understanding the superconducting properties of MgB_2 is based strongly on knowledge of its electronic structure. In this paper we review experimental measurements of the Fermi surface parameters of pure and Al-doped MgB_2 using the de Haas-van Alphen (dHvA) effect. In general, the measurements are in excellent agreement with the theoretical predictions of the electronic structure, including the strength of the electron-phonon coupling on each Fermi surface sheet. For the Al doped samples, we are able to measure how the band structure changes with doping and again these are in excellent agreement with calculations based on the virtual crystal approximation. We also review work on the dHvA effect in the superconducting state.
de Haas-van Alphen effect in single crystal MgB_2  [PDF]
E. A. Yelland,J. R. Cooper,A. Carrington,N. E. Hussey,P. J. Meeson,S. Lee,A. Yamamoto,S. Tajima
Physics , 2001, DOI: 10.1103/PhysRevLett.88.217002
Abstract: We report observations of quantum oscillations in single crystals of the high temperature superconductor MgB_2. Three de Haas-van Alphen frequencies are clearly resolved. Comparison with band structure calculations strongly suggests that two of these come from a single warped Fermi surface tube along the c direction, and that the third arises from cylindrical sections of an in-plane honeycomb network. The measured values of the effective mass range from 0.44-0.68 m_e. By comparing these with band masses calculated recently by three groups, we find that the electron-phonon coupling strength lambda, is a factor \~3 larger for the c-axis tube orbits than for the in-plane network orbit, in accord with recent microscopic calculations.
Damping of the de Haas-van Alphen oscillations in the superconducting state of MgB_2  [PDF]
J. D. Fletcher,A. Carrington,S. M. Kazakov,J. Karpinski
Physics , 2004, DOI: 10.1103/PhysRevB.70.144501
Abstract: The de Haas-van Alphen (dHvA) signal arising from orbits on the $\pi$ Fermi surface sheet of the two-gap superconductor MgB$_2$ has been observed in the vortex state below $H_{c2}$. An extra attenuation of the dHvA signal, beyond those effects described in the conventional Lifshitz-Kosevich expression, is seen due to the opening of the superconducting gap. Our data show that the $\pi$ band gap is still present up to $H_{c2}$. The data are compared to current theories of dHvA oscillations in the superconducting state which allow us to extract estimates for the evolution of the $\pi$ band gap with magnetic field. Contrary to results for other materials, we find that the most recent theories dramatically underestimate the damping in MgB$_2$.
de Haas-van Alphen effect investigation of the electronic structure of Al substituted MgB_2  [PDF]
A. Carrington,J. D. Fletcher,J. R. Cooper,O. J. Taylor,L. Balicas,N. D. Zhigadlo,S. M. Kazakov,J. Karpinski,J. P. H. Charmant,J. Kortus
Physics , 2005, DOI: 10.1103/PhysRevB.72.060507
Abstract: We report a de Haas-van Alphen (dHvA) study of the electronic structure of Al doped crystals of MgB$_2$. We have measured crystals with $\sim 7.5$% Al which have a $T_c$ of 33.6 K, ($\sim 14$% lower than pure MgB$_2$). dHvA frequencies for the $\sigma$ tube orbits in the doped samples are lower than in pure MgB$_2$, implying a $16\pm2%$ reduction in the number of holes in this sheet of Fermi surface. The mass of the quasiparticles on the larger $\sigma$ orbit is lighter than the pure case indicating a reduction in electron-phonon coupling constant $\lambda$. These observations are compared with band structure calculations, and found to be in excellent agreement.
The de Haas - van Alphen Effect Study of the Fermi Surface of ZrB12  [PDF]
V. A. Gasparov,I. Sheikin,F. Levy,J. Teyssier,G. Santi
Physics , 2007,
Abstract: The de Haas - van Alphen (dHvA) effect in the cluster superconductor ZrB12 was studied by magnetic torque measurements in magnetic fields up to 28 T at temperatures down to 0.35 K. The dHvA oscillations due to orbits from the Neck sections and "Cubic Box" of the Fermi surface were detected. We measured cyclotron effective masses of 0.5m_0 for Neck section of the FS. The dHvA frequencies as well as the cyclotron effective masses were calculated using the full potential Linear Muffin-Tin Orbital (LMTO) method within the Generalized Gradient Approximation. Comparison of the angular dependence of the dHvA frequencies with the band-structure calculations implies overall agreement with theoretical model, while one section could not be definitely identified.
Photonic de Haas-van Alphen effect  [PDF]
Kejie Fang,Shanhui Fan
Physics , 2013,
Abstract: Based on the recently proposed concept of effective gauge potential and magnetic field for photons, we numerically demonstrate a photonic de Haas-van Alphen effect. We show that in a dynamically modulated photonic resonator lattice exhibiting an effect magnetic field, the trajectories of the light beam at a given frequency have the same shape as the constant energy contour for the photonic band structure of the lattice in the absence of the effective magnetic field.
De Haas-van Alphen effect in metals without inversion center  [PDF]
V. P. Mineev,K. V. Samokhin
Physics , 2005, DOI: 10.1103/PhysRevB.72.212504
Abstract: We show how the de Haas-van Alphen effect can be used to directly measure the magnitude of spin-orbit coupling in non-centrosymmetric metals, such as CePt3Si and LaPt3Si.
de Haas-van Alphen effect versus Integer Quantum Hall effect  [PDF]
V. P. Mineev
Physics , 2007, DOI: 10.1103/PhysRevB.75.193309
Abstract: In frame of general stastical mechanics approach applied to 2D metal bar we demonstrate the interrelationship between Landau diamagnetism, de Haas-van Alphen magnetization oscillations and the Integer Quantum Hall effect.
On the de Haas - van Alphen oscillations in quasi-two-dimensional metals: effect of the Fermi surface curvature  [PDF]
Natalya A. Zimbovskaya
Physics , 2006, DOI: 10.1088/0953-8984/19/17/176227
Abstract: Here, we present the results of theoretical analysis of the de Haas-van Alphen oscillations in quasi-two-dimensional normal metals. We had been studying effects of the Fermi surface (FS) shape on these oscillations. It was shown that the effects could be revealed and well pronounced when the FS curvature becomes zero at cross-sections with extremal cross-sectional areas. In this case both shape and amplitude of the oscillations could be significantly changed. Also, we analyze the effect of the FS local geometry on the angular dependencies of the oscillation amplitudes when the magnetic field is tilted away from the FS symmetry axis by the angle $\theta.$ We show that a peak appears at $\theta \approx 0$ whose height could be of the same order as the maximum at the Yamaji angle. This peak emerges when the FS includes zero curvature cross-sections of extremal areas. Such maximum was observed in experiments on the $\alpha-(BETS)_4TIHg(SeCN)_4.$ The obtained results could be applied to organic metals and other quasi-two-dimensional compounds.
De Haas-van Alphen effect and Fermi surface properties of single crystal CrB2  [PDF]
M. Brasse,L. Chioncel,J. Kunes,A. Bauer,A. Regnat,C. G. F. Blum,S. Wurmehl,C. Pfleiderer,M. A. Wilde,D. Grundler
Physics , 2013, DOI: 10.1103/PhysRevB.88.155138
Abstract: We report the angular dependence of three distinct de Haas-van Alphen (dHvA) frequencies of the torque magnetization in the itinerant antiferromagnet CrB2 at temperatures down to 0.3K and magnetic fields up to 14T. Comparison with the calculated Fermi surface of nonmagnetic CrB2 suggests that two of the observed dHvA oscillations arise from electron-like Fermi surface sheets formed by bands with strong B-px,y character which should be rather insensitive to exchange splitting. The measured effective masses of these Fermi surface sheets display strong enhancements of up to a factor of two over the calculated band masses which we attribute to electron-phonon coupling and electronic correlations. For the temperature and field range studied, we do not observe signatures reminiscent of the heavy d-electron bands expected for antiferromagnetic CrB2. In view that the B-p bands are at the heart of conventional high-temperature superconductivity in the isostructural MgB2, we consider possible implications of our findings for nonmagnetic CrB2 and an interplay of itinerant antiferromagnetism with superconductivity.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.