scholarly journals Small-Polaron Hopping and Low-Temperature (45–225 K) Photo-Induced Transient Absorption in Magnesium-Doped Lithium Niobate

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 809
Author(s):  
Simon Messerschmidt ◽  
Andreas Krampf ◽  
Laura Vittadello ◽  
Mirco Imlau ◽  
Tobias Nörenberg ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Temperature Regime ◽  
Transient Absorption ◽  
Small Polaron ◽  
Good Representation ◽  
Temperature Dependent ◽  
Polaron Hopping ◽  
Two Parameters ◽  
Oppositely Charged ◽  
Small Polarons

A strongly temperature-dependent photo-induced transient absorption is measured in 6.5 mol% magnesium-doped lithium niobate at temperatures ranging from 45 K to 225 K. This phenomenon is interpreted as resulting from the generation and subsequent recombination of oppositely charged small polarons. Initial two-photon absorptions generate separated oppositely charged small polarons. The existence of these small polarons is monitored by the presence of their characteristic absorption. The strongly temperature-dependent decay of this absorption occurs as series of thermally assisted hops of small polarons that facilitate their merger and ultimate recombination. Our measurements span the high-temperature regime, where small-polaron jump rates are Arrhenius and strongly dependent on temperature, and the intermediate-temperature regime, where small-polaron jump rates are non-Arrhenius and weakly dependent on temperature. Distinctively, this model provides a good representation of our data with reasonable values of its two parameters: Arrhenius small-polaron hopping’s activation energy and the material’s characteristic phonon frequency.

To Be or not to Be: Band-Like Transport in Quantum Dot Solids

2015 ◽  
Vol 229 (1-2) ◽  
Author(s):  
Marcus Scheele
Keyword(s):  
Quantum Dot ◽  
Carrier Transport ◽  
Small Polaron ◽  
Recent Experimental Data ◽  
Supporting Evidence ◽  
Temperature Dependent ◽  
Polaron Hopping ◽  
Hall Effect Measurements ◽  
Plausible Mechanism ◽  
High Degree

AbstractRecent experimental data on charge carrier transport in quantum dot solids is analyzed in light of the question whether band-like transport is the most plausible mechanism to account for the observed behavior. Upon reviewing some physical fundamentals of temperature-activated hopping, small polaron hopping and band-like transport, it is established that a combined approach of different experimental methods is required to achieve a satisfactory degree of unambiguousness to address this question. In doing so, at least one example is identified for which a high degree of supporting evidence exists that transport is in fact diffusive. It is highlighted that temperature-dependent Hall Effect measurements play an important role in this respect.

Electron small polarons and their transport in bismuth vanadate: a first principles study

2015 ◽  
Vol 17 (1) ◽  
pp. 256-260 ◽  
Author(s):  
Kyoung E. Kweon ◽  
Gyeong S. Hwang ◽  
Jinhan Kim ◽  
Sungjin Kim ◽  
SeongMin Kim
Keyword(s):  
Concentration Dependence ◽  
Electron Mobility ◽  
First Principles ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Small Polaron ◽  
Polaron Hopping ◽  
Polaron Formation ◽  
Hybrid Density Functional ◽  
Small Polarons

Hybrid density functional calculations demonstrate small polaron formation in electron-doped BiVO4, and predict the polaron hopping barrier to increase with lattice constant and also the possible concentration-dependence of electron mobility.

SPIN-POLARIZATION DEPENDENT SMALL POLARON HOPPING IN MANGANESE PEROVSKITES

2003 ◽  
Vol 17 (01) ◽  
pp. 25-38
Author(s):  
NING ZHANG
Keyword(s):  
Spin Polarization ◽  
Colossal Magnetoresistance ◽  
Small Polaron ◽  
Double Exchange ◽  
Double Exchange Interaction ◽  
Polaron Hopping ◽  
Colossal Magnetoresistive ◽  
Small Polaron Hopping ◽  
Lattice Effect ◽  
Small Polarons

A model of small polaron hopping being dependent on spin-polarization is suggested to describe the transport and the colossal magnetoresistance behaviors in manganese perovskites R-A-Mn-O (R: rear earth; A: alkali earth or transition metals). Being different from the theory of simple small polarons, the double exchange interaction and some empirical rules related to lattice effect induced by an external magnetic field and changing concentration have been taken into account. Based on this, a simple formula of resistivity versus temperature, concentration and normalized magnetization has been obtained for the hole-doped perovskite. From the formula, most of the transport behaviors including the colossal magnetoresistive observed in the perovskite have been successfully illustrated.

scholarly journals Polaron Trapping and Migration in Iron-Doped Lithium Niobate

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 302
Author(s):  
Laura Vittadello ◽  
Laurent Guilbert ◽  
Stanislav Fedorenko ◽  
Marco Bazzan
Keyword(s):  
Lithium Niobate ◽  
Laser Pulse ◽  
Charge Transport ◽  
Small Polaron ◽  
Deep Trap ◽  
Polaron Hopping ◽  
And Migration ◽  
Kinetics Of ◽  
Photoinduced Charge ◽  
Absorption Measurements

Photoinduced charge transport in lithium niobate for standard illumination, composition and temperature conditions occurs by means of small polaron hopping either on regular or defective lattice sites. Starting from Marcus-Holstein’s theory for polaron hopping frequency we draw a quantitative picture illustrating two underlying microscopic mechanisms besides experimental observations, namely direct trapping and migration-accelerated polaron trapping transport. Our observations will be referred to the typical outcomes of transient light induced absorption measurements, where the kinetics of a polaron population generated by a laser pulse then decaying towards deep trap sites is measured. Our results help to rationalize the observations beyond simple phenomenological models and may serve as a guide to design the material according to the desired specifications.

scholarly journals Small Polaron Hopping in Fe:LiNbO3 as a Function of Temperature and Composition

Crystals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 294 ◽  
Author(s):  
Laura Vittadello ◽  
Marco Bazzan ◽  
Simon Messerschmidt ◽  
Mirco Imlau
Keyword(s):  
Charge Transport ◽  
Transient Absorption ◽  
Small Polaron ◽  
Transient Absorption Spectroscopy ◽  
Relaxation Dynamics ◽  
Experimental Conditions ◽  
Polaron Hopping ◽  
Small Polaron Hopping ◽  
Wide Range ◽  
Temperature Ranges

Small-polaron hopping involved in charge transport in Fe-doped congruent lithium niobate is investigated as a function of temperature and composition by means of light-induced transient absorption spectroscopy. The relaxation dynamics of the light-induced polaron population is characterized by individual activation energies within different temperature ranges. A numerical investigation carried out by Monte Carlo simulations reveals that these findings may be understood in terms of the varying abundance of the different types of hops that the polarons may perform among regular or defective lattice sites. The role of the temperature and of the sample composition on the distribution of the different hop types is thus explored for a wide range of parameters, allowing one to preview the charge transport properties for a given set of experimental conditions.

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