Search results

Sort By:

Limit search:

Metals and Semimetals with Strongly Correlated Electrons

100%

Fulde P.

Acta Physica Polonica A

1997

vol. 91

issue 1

67-76

A characteristic feature of strongly correlated electrons is the appearance of low energy scales. They may result in heavy-quasiparticle excitations at low temperatures. Our understanding of these excitations has been considerably modified over the last few years. While it was originally thought that the Kondo effect is the sole source of heavy-fermion behavior, two additional mechanisms have been identified meanwhile. One is based on the Zeeman effect and occurs in Nd_{2-x}Ce_{x}CuO_{4}. The other is operative in the semimetal Yb_{4}As_{3} and is based on nearly half filled one-dimensional Hubbard chains. In all three cases the low energy excitations result from spin degrees of freedom.

Unconventional Superconductivity, Spontaneous Time-Reversal Symmetry Breaking and Lowering of Kinetic Energy in Doped, Short-Range Antiferromagnets

45%

Wróbel P., Maciąg A., Eder R., Fulde P., Micnas R.

Acta Physica Polonica A

2004

vol. 106

issue 5

575-581

In this paper we focus on the anomalous temperature dependence of the in-plane conductivity and symmetry mixing of the superconducting order parameter observed in various experiments on cuprates. We show that the one-band Hubbard model is not capable of describing the physics of cuprates because the kinetic energy is lowered in this model in the superconducting state, which contradicts experimental observations. The proper model to investigate doped, short-range antiferromagnets is the t-J model, for which our results agree with experiments. We analyze a spin polaron model, that is an effective model for a doped antiferromagnet. In the framework of this model we also study the superconducting order-parameter symmetry-mixing phenomenon. We show that the expected mixing of d-wave symmetry with p-wave symmetry takes place in the superconducting order-parameter at a finite value of the doping parameter. This symmetry mixing brakes the time-reversal symmetry.

Refine search results

2 Acta Physica Polonica A

1 2004

1 1997

2 Fulde P.

1 Eder R.

1 Maciąg A.

1 Micnas R.

1 Wróbel P.

Search results

Metals and Semimetals with Strongly Correlated Electrons

Unconventional Superconductivity, Spontaneous Time-Reversal Symmetry Breaking and Lowering of Kinetic Energy in Doped, Short-Range Antiferromagnets