Optical Sum Rule anomalies in the High-Tc Cuprates (2009)
We provide a brief summary of the observed sum rule anomalies in the high-T$_c$ cuprate materials. A recent issue has been the impact of a non-infinite frequency cutoff in the experiment. In the...
The Harmonic Oscillator in Quantum Mechanics: A Third Way (2008)
Courses on undergraduate quantum mechanics usually focus on solutions of the Schr\"odinger equation for several simple one-dimensional examples. When the notion of a Hilbert space is introduced only...
Electron and Spin Transport in the Presence of Complex Absorbing Potential (2008)
Dogan, Fatih, Kim, Wonkee, Blois, C. M., Marsiglio, F.
We examine the impact of a complex absorbing potential on electron transport, both in the continuum and on a lattice. This requires the use of non-Hermitian Hamiltonians; the required formalism is...
Hole superconductivity in Arsenic-Iron compounds (2008)
Superconductivity above 25K, and possibly above 40K, has recently been discovered in $LaO_{1-x}F_xFeAs$ and related compounds. We propose that this is another example of the mechanism of hole...
Hall Conductivity in a Spin-Triplet Superconductor (2007)
Kim, Wonkee, Marsiglio, F., Ting, C. S.
We calculate the Hall conductivity for a spin-triplet superconductor, using a generalized pairing symmetry dependent on an arbitrary phase, $\vphi$. A promising candidate for such an order parameter...
Impact of a finite cut-off for the optical sum rule in the superconducting state (2007)
Marsiglio, F., Van Heumen, E., Kuzmenko, A. B.
A single band optical sum rule derived by Kubo can reveal a novel kind of superconducting state. It relies, however, on a knowledge of the single band contribution from zero to infinite frequency. A...
Electron-phonon effects on spin-orbit split bands of two dimensional systems (2007)
Cappelluti, E., Grimaldi, C., Marsiglio, F.
The electronic self-energy is studied for a two dimensional electron gas coupled to a spin-orbit Rashba field and interacting with dispersionless phonons. For the case of a momentum independent...
Quantum mechanics of spin transfer in coupled electron-spin chains (2007)
Kim, Wonkee, Covaci, L., Dogan, F., Marsiglio, F.
The manner in which spin-polarized electrons interact with a magnetized thin film is currently described by a semi-classical approach. This in turn provides our present understanding of the spin...
Model-Independent Sum Rule Analysis Based on Limited-Range Spectral Data (2007)
Kuzmenko, A. B., Carbone, F., Marsiglio, F.
Partial sum rules are widely used in physics to separate low- and high-energy degrees of freedom of complex dynamical systems. Their application, though, is challenged in practice by the always...
Cappelluti, E., Grimaldi, C., Marsiglio, F.
Strong spin-orbit coupling can have a profound effect on the electronic structure in a metal or semiconductor, particularly for low electron concentrations. We show how, for small values of the Fermi...
Optical properties and electronic structure of ZrB$_{12}$ (2006)
Teyssier, J., Kuzmenko, A. B., Marsiglio, F., Liashchenko, A. B., Filippov, V., ...
We report optical (6 meV - 4 eV) properties of a boride superconductor ZrB$_{12}$ ($T_c$ = 6 K) in the normal state from 20 to 300 K measured on high-quality single crystals by a combination of...
Marsiglio, F., Carbone, F., Kuzmenko, A.
The Kubo single band sum rule is used to determine the optical spectral weight of a tight binding band with further than nearest neighbour hopping. We find for a wide range of parameters and doping...
Spin-Hall Conductivity in Electron-Phonon Coupled Systems (2006)
Grimaldi, C., Cappelluti, E., Marsiglio, F.
We derive the ac spin-Hall conductivity $\sigma_{\rm sH}(\omega)$ of two-dimensional spin-orbit coupled systems interacting with dispersionless phonons of frequency $\omega_0$. For the linear Rashba...
Carbone, F., Kuzmenko, A. B., Molegraaf, H. J. A., Van Heumen, E., Lukovac, V., Marsiglio, F., ...
We present the ab-plane optical conductivity of four single crystals of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ (Bi2212) with different carrier doping levels from the strongly underdoped to the...
Impurity Scattering of Wave Packets on a Lattice (2006)
Kim, Wonkee, Covaci, L., Marsiglio, F.
Quantum transport in a lattice is distinct from its counterpart in continuum media. Even a free wave packet travels differently in a lattice than in the continuum. We describe quantum scattering in a...
Benfatto, L., Carbotte, J. P., Marsiglio, F.
We examine the temperature dependence of the optical sum rule in the normal state due to interactions. To be concrete we adopt a weak coupling approach which uses an electron-boson exchange model to...
Observation of phonon structure in electron density of states of normal metal (2006)
Knigavko, A., Carbotte, J. P., Marsiglio, F.
Within standard treatments of the interacting electron--phonon system the electron density of states (EDOS) shows no sign of the phonons when the system is in the normal state. On the other hand,...
Hidden Symmetries of Electronic Transport in a Disordered One-Dimensional Lattice (2006)
Kim, Wonkee, Covaci, L., Marsiglio, F.
Correlated, or extended, impurities play an important role in the transport properties of dirty metals. Here, we examine, in the framework of a tight-binding lattice, the transmission of a single...
Grimaldi, C., Cappelluti, E., Marsiglio, F.
We calculate the spin-Hall conductivity of a disordered two-dimensional Rashba electron gas within the self-consistent Born approximation and for arbitrary values of the electron density,...
How many electrons are needed to flip a local spin? (2004)
Kim, Wonkee, Teshima, R. K., Marsiglio, F.
Considering the spin of a local magnetic atom as a quantum mechanical operator, we illustrate the dynamics of a local spin interacting with a ballistic electron represented by a wave packet. This...
Pairing Fluctuations in The Attractive Hubbard Model in the Atomic Limit (2004)
Verga, S., Gooding, R. J., Marsiglio, F.
BCS theory accounts for the pairing instability in the weak coupling limit, but fails to describe pairing fluctuations above $T_c$. One possibility for describing these fluctuations in the dilute...
Quantum Mechanics of Spin Transfer in Ferromagnetic Multilayers (2004)
We use a quantum mechanical treatment of a ballistic spin current to describe novel aspects of spin transfer to a ferromagnetic multilayer. We demonstrate quantum phenomena from spin transmission...
Optical sum increase due to electron undressing (2004)
Knigavko, A., Carbotte, J. P., Marsiglio, F.
For a system with a fixed number of electrons, the total optical sum is a constant, independent of many-body interactions, of impurity scattering and of temperature. For a single band in a metal,...
Microwave Conductivity of a High Purity d-wave Superconductor (2004)
Kim, Wonkee, Marsiglio, F., Carbotte, J. P.
The cusp-like behavior of the microwave conductivity observed in clean ortho-II YB$_{2}$Cu$_{3}$O$_{6.50}$ at low temperature and low frequency is shown to be related directly to a linear in...
Demonstration of a robust pseudogap in a three-dimensional correlated electronic system (2004)
Gooding, R. J., Marsiglio, F., Verga, S., Beach, K. S. D.
We outline a partial-fractions decomposition method for determining the one-particle spectral function and single-particle density of states of a correlated electronic system on a finite lattice in...
Spin Torque and its Relation to Spin Filtering (2003)
The spin torque exerted on a magnetic moment is a reaction to spin filtering when spin-polarized electrons interact with a thin ferromagnetic film. We show that, for certain conditions, a spin...
Kim, Wonkee, Marsiglio, F., Carbotte, J. P.
We show that the Wiedemann-Franz law is violated at zero temperature in the vortex state of a d-wave BCS superconductor with isotropic impurity scattering. We use a semiclassical approach to include...
Dynamics of a magnetic moment induced by a spin-polarized current (2003)
Effects of an incoming spin-polarized current on a magnetic moment are explored. We found that the spin torque occurs only when the incoming spin changes as a function of time inside of the magnetic...
Dynamic Hubbard Model: Effect of Finite Boson Frequency (2003)
Marsiglio, F., Teshima, R., Hirsch, J. E.
Dynamic Hubbard models describe coupling of a boson degree of freedom to the on-site electronic double occupancy. In the limit of infinite boson frequency this coupling gives rise to a correlated...
Kim, Wonkee, Marsiglio, F., Carbotte, J. P.
The low temperature thermal conductivity of a d-wave superconductor is considered for arbitrary strength of the impurity potential. A random distribution of vortices is included within the usual...
Wiedemann-Franz violation in the vortex state of a d-wave superconductor (2003)
Kim, Wonkee, Marsiglio, F., Carbotte, J. P.
We show that the Wiedemann-Franz law is violated in the vortex state of a d-wave superconductor at zero temperature. We use a semiclassical approach, which includes the Doppler shift on the...
Microscopic study of inhomogeneous superconductors (2003)
We study various inhomogeneity effects on superconductivity as due to quantum confinement, surfaces and impurities, using the self-consistent Bogoliubov-de Gennes formalism on the attractive Hubbard...
S-wave superconductivity near a surface (2003)
We study the superconducting order parameter near a surface with the Bogoliubov-de Gennes formalism. For definiteness we use the attractive Hubbard model. Near a surface, the order parameter and the...
Yang, Y. S., Marsiglio, F., Madsen, M., Gaulin, B. D., Rogge, R. B., Fernandez-Baca, J. A.
Inelastic neutron scattering profiles of spin waves in the dilute quasi-one-dimensional Ising-like antiferromagnet CsCo_{0.83}Mg_{0.17}Br_3 have been investigated. Calculations of S^{xx}(Q,omega),...
Inversion of ARPES measurements in high Tc cuprates (2002)
Verga, S., Knigavko, A., Marsiglio, F.
Recent energy dispersion measurements in several families of the hole-doped copper oxides have revealed a kink in the energy vs. momentum relation. These have tentatively been identified as due to...
Sum rule for the optical scattering rates (2001)
Marsiglio, F., Carbotte, J. P., Schachinger, E.
An important quantity in electronic systems is the quasiparticle scattering rate (QPSR). A related optical scattering rate (OSR) is routinely extracted from optical data, and, while it is not the...
Implications of reflectance measurements on the mechanism for superconductivity in MgB$_2$ (2001)
Recent optical studies in c-axis oriented superconducting MgB$_2$ films indicate that the electron-phonon coupling is weak [tu01]. We reinforce this conclusion by examining the raw reflectance data;...
Electron - Phonon Superconductivity (2001)
Marsiglio, F., Carbotte, J. P.
In this chapter we review the essentials of conventional electron-phonon superconductivity, as provided through the Migdal-Eliashberg formalism. Signatures of the electron-phonon interaction, as they...
Constraints from $T_c$ and the isotope effect for MgB$_2$ (2001)
With the constraint that $T_c = 39$ K, as observed for MgB$_2$, we use the Eliashberg equations to compute possible allowed values of the isotope coefficient, $\beta$. We find that while the observed...
Electron-Phonon or Hole Superconductivity in $MgB_2$? (2001)
The BCS electron-phonon mechanism and the unconventional 'hole mechanism' have been proposed as explanations for the high temperature superconductivity observed in $MgB_2$. It is proposed that a...
Feedback effects and the self-consistent Thouless criterion of the attractive Hubbard model (2000)
Beach, K. S. D., Gooding, R. J., Marsiglio, F.
We propose a fully microscopic theory of the anomalous normal state of the attractive Hubbard model in the low-density limit that accounts for propagator renormalization. Our analytical conclusions,...
Optical sum rule violation, superfluid weight and condensation energy in the cuprates (2000)
The model of hole superconductivity predicts that the superfluid weight in the zero-frequency $\delta$-function in the optical conductivity has an anomalous contribution from high frequencies, due to...
Anisotropic penetration depth and optical sum rule violation in La_(2-x)Sr_xCuO_4 (2000)
We calculate the doping dependence of the penetration depths and optical sum rule violation in La_(2-x)Sr_xCuO_4 within the model of hole superconductivity. In the clean limit the predicted in-plane...
The Anderson prescription for surfaces and impurities (2000)
We test the Anderson prescription [1], a BCS formalism for describing superconductivity in inhomogeneous systems, and compare results with those obtained from the Bogoliubov-de Gennes formalism,...
Anderson's "Theorem" and Bogoliubov-de Gennes Equations for Surfaces and Impurities (2000)
In order to incorporate spatial inhomogeneity due to nonmagnetic impurities, Anderson [1] proposed a BCS-type theory in which single-particle states in such an inhomogeneous system are used. We...
Fixed Number and Quantum Size Effects in Nanoscale Superconductors (1999)
In recent experiments on nanoscale Al particles, whose electron number was fixed by charging effects, a ``negative gap'' was observed in particles with an odd number of electrons. This observation...
New Solutions of the T-Matrix Theory of the Attractive Hubbard Model (1999)
Beach, K. S. D., Gooding, R. J., Marsiglio, F.
This short paper summarizes a calculational method for obtaining the dynamical properties of many-body theories formulated in terms of (unrenormalized) bare propagators (and more generally, in terms...
Beach, K. S. D., Gooding, R. J., Marsiglio, F.
We critique a Pade analytic continuation method whereby a rational polynomial function is fit to a set of input points by means of a single matrix inversion. This procedure is accomplished to an...
Where is 99% of the condensation energy of Tl_2Ba_2CuO_y coming from? (1999)
Anderson's interlayer tunneling model can account for up to 1% of the condensation energy of Tl_2Ba_2CuO_y. Here we account for the remaining 99%. We predict an in-plane kinetic energy gain of 1 to 3...
Electronic Shell Structure of Nanoscale Superconductors (1999)
Motivated by recent experiments on Al nanoparticles, we have studied the effects of fixed electron number and small size in nanoscale superconductors, by applying the canonical BCS theory for the...
A system of equations resulting from an approximation of the equation of motion of Green functions for correlated electron systems is usually solved using Matsubara technique. In this work we propose...
Canonical BCS Approximation for the Attractive Hubbard Model (1999)
We test the canonical BCS wave functions for fixed number of electrons for the attractive Hubbard model. We present results in one dimension for various chain lengths, electron densities, and...
Even-Odd and Super-Even Effects in the Attractive Hubbard Model (1999)
The canonical BCS wave function is tested for the attractive Hubbard model. Results are presented for one dimension, and are compared with the exact solutions by the Bethe ansatz and the results from...
Inversion of Optical Reflectance in the Fullerenes (1998)
Since the discovery of superconductivity in the alkali-doped fullerenes \cite{hebard}, the electron-phonon interaction has been the primary suspect for superconductivity in this class of compounds....
Inversion of K$_3$C$_{60}$ Reflectance Data (1998)
Marsiglio, F., Startseva, T., Carbotte, J. P.
We outline a procedure for obtaining the electron-phonon spectral density by inversion of optical conductivity data, a process very similar in spirit to the McMillan-Rowell inversion of tunelling...
Quasiparticle Lifetimes and the Conductivity Scattering Rate (1997)
Marsiglio, F., Carbotte, J. P.
We compute the single-particle inverse lifetime, along with the conductivity-derived scattering rate, for a metallic system in an s-wave superconducting state. When both electron-phonon and...
Evaluation of the BCS Approximation for the Attractive Hubbard Model in One Dimension (1996)
The ground state energy and energy gap to the first excited state are calculated for the attractive Hubbard model in one dimension using both the Bethe Ansatz equations and the variational BCS...
The Imaginary Part of the Optical Conductivity of $Ba_{1-x}K_xBiO_3$ (1996)
Marsiglio, F., Carbotte, J. P., Puchkov, A., Timusk, T.
The frequency dependence of the imaginary part of the infrared conductivity is calculated for a superconductor. Sharp structure, characteristic of superconductivity with an order parameter with...
Marsiglio, F., Carbotte, J. P.
We compute the single particle inverse lifetime, evaluated in the superconducting state. Within the BCS framework, the calculation can be done non-perturbatively, i.e. poles can be found well away...