arXiv subjects
Publications and source records attributed to Philip W. Anderson.
The question of whether a Bose solid can have a superfluid fraction in the absence of interstitials, holes or other defects is discussed. An unlikely scenario which may accommodate this possibility is proposed, based on a Hartree-Fock treatment of the quantum solid. It is now believed that this version is correct
After reviewing some experimental facts, and early theories, I sketch the Hartree-Fock description of Boson solids, emphasizing the contrast with the Fermion case in that the natural solution is a product of local wave-functions. I then investigate the Boson Hubbard model to demonstrate that the local functions are not orthogonal and exemplify a novel state of matter which has superflow but not ODLRO, below a cooperative thermal transition. I then discuss whether or not these ideas actually apply to solid He.
Hidden Fermi liquid theory explicitly accounts for the effects of Gutzwiller projection in the t-J Hamiltonian, widely believed to contain the essential physics of the high-Tc superconductors. We derive expressions for the entire "strange metal", normal state relating angle-resolved photoemission, resistivity, Hall angle, and by generalizing the formalism to include the Fermi surface topology - angle-dependent magnetoresistance. We show this theory to be the first self-consistent description for the normal state of the cuprates based on transparent, fundamental assumptions. Our well-defined formalism also serves as a guide for further experimental confirmation.
Anderson has recently proposed a theory of the strange metal state above Tc in the high Tc superconductors. [arXiv:cond-mat/0512471] It is based on the idea that the unusual transport properties and spectral functions are caused by the strong Mott- Hubbard interactions and can be computed by using the formal apparatus of Gutzwiller projection. In ref. 1 Anderson computed only the tunneling spectrum and the power-law exponent of the infrared conductivity. He had calculated the energy distribution curves (EDCs) in angle resolved photoemission spectroscopy (ARPES) but was discouraged when these differed radically from the best ARPES measurements available at the time, and did not include them. In this letter we compare the spectral functions computed within this model to the novel laser-ARPES data of the Dessau group.These are found to capture the shape of the experimental EDCs with unprecedented accuracy and in principle have only one free parameter.
Many investigators have joined the search for a bosonic glue which is hypothecated to be the mechanism which binds the electron pairs in the cuprate high Tc superconductors, often referring to the Eliashberg formalism which was developed to reveal the role of phonons in the conventional polyelectronic metal superconductors. In this paper we point out that the picture of boson exchange is a folklore description of the pairing process with no rigorous basis. The problem of pairing is always that of evading the strong Coulomb vertex, the repulsive core of the interaction; we discuss the different means by which the two types of superconductors accomplish this feat.
In recent years a fashion has grown up to ascribe great importance to ``quantum critical points'' at T=0, at the boundary between the basins of attraction to the stable fixed points of ordered ground states. I argue that more physical significance in connecting microscopic interactions with observed phenomena lies in the common phenomenon of partially ordered ``liquid'' states at higher temperatures, unstable phases which define the relevant degrees of freedom and may order in many different ways as the temperature is further lowered.
I discuss various direct calculations of the properties of the one-band Hubbard model on a square lattice and conclude that these properties sufficiently resemble those of the cuprate superconductors that no more complicated interactions are necessary to cause high Tc superconductivity.. In particular, I discuss phonon effects and conclude that these may be effective in reducing Tc and the gap in electron-doped materials.
It is argued that the dominant feature of the phase diagram of the high $T_c$ cuprates is the crossover to the pseudogap phase in the energy (temperature) region $E (T^*)$. We argue that this scale is determined by the effective antiferromagnetic interaction which we calculate to be $J_{eff} = J_{\rm superexchange} - xt$ where $x$ is the hole percentage and $t$ the hopping integral.
We propose that early speculations on the nature of the normal state of the $CuO_2$ planes in high $T_c$ superconductors can be revised and brought into agreement with more modern theories, simulations and experimental observations.
A number of authors have taken issue with the demonstration that the 2D Fermion gas with short-range repulsive interactions (and, of course, including spin) cannot be consistently treated as a renormalised quasiparticle system. This paper shows that the arguments given in some of these papers are invalid or irrelevant.
We point out that the quasiparticle spectrum of the Landau Fermi liquid theory has an extra $Z_2$ symmetry, local in momentum space, which is not generic to the Hamiltonian with interactions. Thus the Fermi liquid is in this sense a (quantum) zero-temperature critical point.
We find experimental evidence for spin-charge separation in all four relevant phases of the cuprates. It is argued that this phenomenon serves to protect the properties of the cuprates from the effects of impurities and phonons.
We argue that spin charge separation holds the key to the understanding of high temperature superconductivity.
I derive equations of motion for quasiparticles near the nodes in the d-wave gap of high Tc superconductors. Previous versions have not properly taken into account the spatial dependence of the gap parameter phase. The results are compatible with magnetothermal conductivity measurements in the superconducting phase by Ong and Krishana.
This paper was given at the Santa Barbara workshop on non-Fermi Liquids, June 1996. It was delayed in posting by a clerical error.
This paper has been submitted to Science. It summarizes the experimental evidence for (and against) the interlayer theory. It was delayed in posting by clerical error.
This paper was submitted to Phys. Rev. Lett in an earlier version. This version was published in my book. It was delayed in posting by a clerical error.
A simple interlayer pair tunneling is solved exactly. We find that in the normal state spin-1/2 particle and hole excitations are gapped. But the state is an unusual metal, characterized by novel fermionic spin zero and charge +2e and -2e excitations that exist about their own Fermi surfaces. The model is consistent with a number of properties of the underdoped cuprates. At finite temperature the Fermi surface appears partially gapped, and at high temperatures the spin gap disappears completely. Superconductivity is induced by an additional intralyer interaction which opens a gap in the charge-fermion spectrum. The symmetry of this charge gap (and hence that of the order parameter) is igenerally different from the symmetry of one-electron or - hole gap. The former can be a d wave, while the latter is more complex.