arXiv subjects

M. I. Auslender

Publications and source records attributed to M. I. Auslender.

3 recordsLinked to original sources

arXiv2008

The Effective Spin Hamiltonian and Phase Separation Instability of the Almost Half-Filled Hubbard Model and Narrow-Band {\it S-f} Model

The effective spin Hamiltonian is constructed in the framework of the almost half-filled Hubbard model on the Cayley tree by means of functional integral technique with the use of static approximation. The system in the ground state appears to be consisting of the ferromagnetic metallic domains and the antiferromagnetic insulating one sprovided that the concentration of excess electrons (or holes) does not exceed some critical value. The connection between the Hubbard model and the {\it s-f} model is stated. Note added: This posting is intended to show that the phase separation in strongly correlated electronic systems was considered already in 1970-80's and is not a discovery of latest manganites boom

cond-mat.str-el↗

arXiv2006

Electron self-trapping at quantum and classical critical points

Using Feynman path integral technique estimations of the ground state energy have been found for a conduction electron interacting with order parameter fluctuations near quantum critical points. In some cases only \textit{singular} perturbation theory in the coupling constant emerges for the electron ground state energy. It is shown that an autolocalized state (quantum fluctuon) can be formed and its characteristics have been calculated depending on critical exponents for both weak and strong coupling regimes. The concept of fluctuon is considered also for the classical critical point (at finite temperatures) and the difference between quantum and classical cases has been investigated. It is shown that, whereas the quantum fluctuon energy is connected with a true boundary of the energy spectrum, for classical fluctuon it is just a saddle-point solution for the chemical potential in the exponential density of states fluctuation tail.

cond-mat.stat-mech↗

arXiv2005

Electron self-trapping and fluctuation density-of-states tail at the critical point

We consider electron self-trapping due to its interaction with order-parameter fluuctuations at the second-order phase-transition or critical point (for example, at the Curie temperature in magnetic or ferroelectric semiconductors). Using Feynman path integral approach the autolocalization energy and the size of the self-trapped state (fluctuon) are estimated. It is shown that the fluctuon states are connected with the Lifshitz tail of the electron density-of-states, the parameters of this tail being determined by the critical exponents.

cond-mat.stat-mech↗