arXiv subjects

M. Niţă

Publications and source records attributed to M. Niţă.

3 recordsLinked to original sources

arXiv2026

Topological edge states of the hexagonal linear chain

We study the eigenspectrum properties of a one-dimensional molecular chain composed of hexagonal unit cells. The system features two alternating hopping parameters, resulting in a rich energy spectrum with both dispersive and flat bands. By analyzing the model under periodic and open boundary conditions, we identify two insulating phases separated by a gap-closing transition controlled by the ratio of hopping amplitudes. In the topological phase, realized when the hopping ratio falls below a critical value, edge states emerge that are exponentially localized at the boundaries of finite chains.

cond-mat.mes-hall↗

arXiv2013

Spectral and transport properties of the two-dimensional Lieb lattice

The specific topology of the line centered square lattice (known also as the Lieb lattice) induces remarkable spectral properties as the macroscopically degenerated zero energy flat band, the Dirac cone in the low energy spectrum, and the peculiar Hofstadter-type spectrum in magnetic field. We study here the properties of the finite Lieb lattice with periodic and vanishing boundary conditions. We find out the behavior of the flat band induced by disorder and external magnetic and electric fields. We show that in the confined Lieb plaquette threaded by a perpendicular magnetic flux there are edge states with nontrivial behavior. The specific class of twisted edge states, which have alternating chirality, are sensitive to disorder and do not support IQHE, but contribute to the longitudinal resistance. The symmetry of the transmittance matrix in the energy range where these states are located is revealed. The diamagnetic moments of the bulk and edge states in the Dirac-Landau domain, and also of the flat states in crossed magnetic and electric fields are shown.

cond-mat.mes-hall↗

arXiv2010

Analyzing the measured phase in the multichannel Aharonov-Bohm interferometer

We address the quantum dot phase measurement problem in an open Aharonov-Bohm interferometer, assuming multiple transport channels. In such a case, the quantum dot is characterized by more than one intrinsic phase for the electrons transmission. It is shown that the phase which would be extracted by the usual experimental method (i.e. by monitoring the shift of the Aharonov-Bohm oscillations, as in Schuster {\it et al.}, Nature {\bf 385}, 417 (1997)) does not coincide with any of the dot intrinsic phases, but is a combination of them. The formula of the measured phase is given. The particular case of a quantum dot containing a $S=1/2$ spin is discussed and variations of the measured phase with less than $π$ are found, as a consequence of the multichannel transport.

cond-mat.mes-hall↗