Showing papers by "C. A. Balseiro published in 1979"
TL;DR: In this paper, the interdependence of superconductivity and charge density wave (CDW) states is discussed, and the tendency toward the formation of SC and CDW are to a certain degree opposing one another.
Abstract: Publisher Summary Superconductivity (SC) and charge-density wave (CDW) are the two most well-known cases of broken symmetry in a solid, which require an effective attractive electron–electron interaction. That interaction is normally provided by a phonon-mediated mechanism. It is therefore to be expected that systems in which CDWs have been experimentally observed also exhibit SC at very low temperatures. The tendencies toward the formation of SC and CDW are to a certain degree opposing one another. While the SC state has infinite conductivity and a Meissner effect, the CDW state, for large enough interactions, produces a semiconductor gap in the spectrum and a nonconducting state. From a microscopic point of view, on the other hand, the SC state arises from electron–electron coupling into Cooper pairs and the CDW state arises from electron-hole coupling and charge redistribution. These two effects are in principle independent of one another. This chapter discusses the interdependence of the SC and CDW states.
104 citations
TL;DR: In this paper, a theory of superconductivity for metals in which there are localized spins is presented, and the spins interact with the conduction electrons via an exchange interaction and with one another via a direct Heisenberg interaction, as well as indirectly via conduction electron.
Abstract: In this paper a theory of superconductivity for metals in which there are localized spins is presented. The spins interact with the conduction electrons via an exchange interaction and with one another via a direct Heisenberg interaction, as well as indirectly via the conduction electrons. The spins are treated as classical vectors in a mean-field approximation. The superconducting pair-breaking mechanism is treated in the approximation of Abrikosov and Gor'kov. Complete interplay of magnetization and pair-breaking processes is taken into account. Phase diagrams are presented. A treatment of alloys of two different magnetic ions is included in a simple approximation. All results are in good qualitative agreement with the experiment.
15 citations
TL;DR: In this article, the authors applied the previously introduced formalism to study the properties of some intermediate-valence solids to calculate the magnetic susceptibility of various models and the instabilities of the paramagnetic state against ferromagnetic and antiferromagnetism.
Abstract: The previously introduced formalism to study the properties of some intermediate-valence solids is applied to calculate the magnetic susceptibility of various models and the instabilities of the paramagnetic state against ferromagnetism and antiferromagnetism Our main results are: (i) A considerably enhanced susceptibility consisting of (a) a Hubbard-type Pauli contribution and (b) a Van-Vleck-type term due to higher configuration admixing (ii) Instabilities against ferromagnetism and antiferromagnetism which are independent of the Van Vleck-type contribution and which differ somewhat from similar divergences found in the Hubbard model
10 citations