arXiv subjects

S. M. Yakubenya

Publications and source records attributed to S. M. Yakubenya.

5 recordsLinked to original sources

arXiv2020

Manifestations of the electron-phonon interaction range in angle resolved photoemission spectra

Numerous angle resolved photoemission spectroscopy (ARPES) studies of a wide class of low-density metallic systems, ranging from doped transition metal oxides to quasi two-dimensional interfaces between insulators, exhibit phonon sidebands below the quasi-particle peak as a unique hallmark of polaronic correlations. Here, we single out properties of ARPES spectra that can provide a robust estimate of the effective range (screening length) of the electron-phonon interaction, regardless of the limited experimental resolution, dimensionality and particular features of the electronic structure, facilitating a general methodology for an analysis of a whole class of materials.

cond-mat.str-el↗

arXiv2016

On the photoinduced phase transition in (GeTe)n(Sb2Te3)m

We suggest a phenomenological description of the photo-conversion in Ge-Sb-Te phase-change memory alloys from amorphous to crystalline phase which explains why both photo-excitation and high temperatures T > 160C are required for the transition from hexagonal to tetrahedral phase. The position of chemical potential at high temperatures allows light induced inverse population of the nucleons of the crystalline phase which are not stable otherwise. Then, inverse population accumulates holes on neighboring Te and Ge ions and locks the photo-conversion transition by pushing Ge ions into the interstitial position to minimize the Coulomb repulsion energy.

cond-mat.mtrl-sci↗

arXiv2016

About anomalous g-factor value of Mn related defects in GaAs:Mn

The results of experimental investigations of ESR spectra of manganese impurity ions in a GaAs : Mn system are presented. The studies are done for various a Fermi level position relative to valence band edge in the system. Characteristic defects for the system that give rise to lines with g factors of 5.62 and 2.81 in the ESR spectra are studied in some detail. The experimental results are discussed in the framework of a previously developed model with a double defect involving the impurity ion. The "3d5 + hole" model is a special case of the double defect model in this system. An analytical expression for the covalent renormalization of the g factor of an ESR line in this system is obtained.

cond-mat.mtrl-sci↗

arXiv2011

A Manganise Ions Ground State in Mn_xSi_{1-x} : Negative - U Properties Centre?

The properties of magnetic deluted and strong correlated systems of MnxSi1-x systems are discussed. In frame work of the model of the double defects including manganese ion and silicon vacancy are considered properties of these systems. The role of the Jahn -Teller distortions of different symmetry types in MnSi system magnetic-properties formation is discussed. It has been established that defect {Mns+1 - Vsio} is the center with negative-U properties and Jahn-Teller's full symmetric vibration mode initiates change of a crystal-field value from intermediate (a configuration - {Mns+1 - Vsio}) to strong (a configuration -{Mns-1 - Vsi+2}).

cond-mat.str-el↗

arXiv2008

A possible mechanism of ultrafast amorphization in phase-change memory alloys: an ion slingshot from the crystalline to amorphous position

We propose that the driving force of an ultrafast crystalline-to-amorphous transition in phase-change memory alloys are strained bonds existing in the (metastable) crystalline phase. For the prototypical example of GST, we demonstrate that upon breaking of long Ge-Te bond by photoexcitation Ge ion shot from an octahedral crystalline to a tetrahedral amorphous position by the uncompensated force of strained short bonds. Subsequent lattice relaxation stabilizes the tetrahedral surroundings of the Ge atoms and ensures the long-term stability of the optically induced phase.

cond-mat.mtrl-sci↗