Colossal Magnetoresistance of Layered Manganite La1.2Sr1.8Mn2O7 and Its Description by a “Spin–Polaron” Conduction Mechanism

2018 ◽  
Vol 60 (6) ◽  
pp. 1078-1081 ◽  
Author(s):  
S. A. Gudin ◽  
N. I. Solin ◽  
N. N. Gapontseva
Keyword(s):  
Colossal Magnetoresistance ◽  
Conduction Mechanism ◽  
Spin Polaron ◽  
Polaron Conduction

scholarly journals Колоссальное магнитосопротивление слоистого манганита La-=SUB=-1.2-=/SUB=-Sr-=SUB=-1.8-=/SUB=-Mn-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- и его описание "спин-поляронным" механизмом проводимости

2018 ◽  
Vol 60 (6) ◽  
pp. 1067
Author(s):  
С.А. Гудин ◽  
Н.И. Солин ◽  
Н.Н. Гапонцева
Keyword(s):  
Colossal Magnetoresistance ◽  
Conduction Mechanism ◽  
Fold Increase ◽  
Spin Polaron ◽  
Electric Conduction ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Conduction Mechanisms ◽  
Orientation Mechanism ◽  
Activation Type

AbstractThe resistance of a La_1.2Sr_1.8Mn_2(1– z )O_7 single crystal has been studied in magnetic fields from 0 to 90 kOe. The magnetoresistance at temperature T = 75 K, near which a colossal magnetoresistance maximum is observed, has been successfully described in terms of the “spin–polaron” electric conduction mechanism. This value of the colossal magnetoresistance is due to a three-fold increase in the polaron size. The method of separating contributions of various conduction mechanisms to the magnetoresistance developed for materials with activation type of conduction is generalized to compounds in which a metal–insulator transition is observed. It is found that, at a temperature of 75 K, the contribution of the “orientation” mechanism is maximum (≈20%) in a magnetic field of 5 kOe and almost disappears in fields higher than 50 kOe.

scholarly journals Описание колоссального магнитосопротивления La-=SUB=-1.2-=/SUB=-Sr-=SUB=-1.8-=/SUB=-Mn-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- на основе "спин-поляронного" и "ориентационного" механизмов проводимости в парамагнитной области температур

2020 ◽  
Vol 62 (5) ◽  
pp. 669
Author(s):  
С.А. Гудин ◽  
Н.И. Солин
Keyword(s):  
Magnetic Field ◽  
Colossal Magnetoresistance ◽  
Main Role ◽  
Spin Polaron ◽  
Temperature Range ◽  
Conduction Mechanisms ◽  
Theoretical Investigations ◽  
Temperature Dependences ◽  
The Magnetic Field ◽  
Good Agreement

Experimental and theoretical investigations of the resistance of the La1.2Sr1.8Mn2O7 single crystal in magnetic fields from 0 to 90 kOe and in the temperature range from 75 to 300 K has been studied. The magnetoresistance is determined by the “spin-polaron” and “orientation” conduction mechanisms. Using the method of separating contributions to the magnetoresistance from several conduction mechanisms, the observed magnetoresistance of La1.2Sr1.8Mn2O7 manganite in the temperature range of 75-300 K is described, good agreement between the calculated and experimental data is obtained. In a magnetic field of 0 and 90 kOe, the temperature dependences of the size of the spin polaron (in relative units) are calculated for the temperature range 75–300 K. It is shown, that the КМС value is determined by an increase in the linear size of the spin polaron (along the magnetic field), i.e. the main role in the magnitude of the colossal magnetoresistance is made by the change in the size of the magnetic inhomogeneities of the crystal.

POLARON AND SPIN-POLARON EFFECTS IN THE COLOSSAL MAGNETORESISTANCE

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3808-3814 ◽  
Author(s):  
Y. M. MALOZOVSKY ◽  
J. D. FAN
Keyword(s):  
Phase Transition ◽  
Colossal Magnetoresistance ◽  
Manganese Oxides ◽  
Spin Diffusion ◽  
Magnetic Moments ◽  
Spin Fluctuations ◽  
Ferromagnetic Phase ◽  
Spin Polaron ◽  
Ferromagnetic Phase Transition ◽  
Polaron Formation

The polaron formation due to the strong interaction of electrons with the optical phonons in a layered manganese oxides is considered. The diffusion of nearly localized polarons in the presence of the spin-dependent and multiple scattering on the randomly oriented and/or distributed magnetic moments of atoms is considered. The spin diffusion coefficient in the case of the exchange interaction between the diffusive but nearly localized polarons is evaluated. It is shown that the polaron localization leads to the vanishing of the spin diffusion and hence the ferromagnetic phase transition. The spin-polaron effect caused by the interaction of polarons with the spin fluctuations further significantly reduces conductivity near the temperature of the ferromagnetic phase transition as shown.

scholarly journals Mechanistic insights of enhanced spin polaron conduction in CuO through atomic doping

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Tyler J. Smart ◽  
Allison C. Cardiel ◽  
Feng Wu ◽  
Kyoung-Shin Choi ◽  
Yuan Ping
Keyword(s):  
Spin Polaron ◽  
Polaron Conduction

Polaron conduction mechanism in Nickel ferrite and its rare-earth derivatives

2021 ◽  
Vol 606 ◽  
pp. 412819
Author(s):  
Kodam Ugendar ◽  
G. Markandeyulu ◽  
Shanigaram Mallesh
Keyword(s):  
Rare Earth ◽  
Nickel Ferrite ◽  
Conduction Mechanism ◽  
Polaron Conduction

scholarly journals Defects and polaronic electron transport in Fe2WO6

2020 ◽  
Vol 22 (27) ◽  
pp. 15541-15548
Author(s):  
Raphael Schuler ◽  
Truls Norby ◽  
Helmer Fjellvåg
Keyword(s):  
Electron Transport ◽  
Oxygen Vacancies ◽  
Conduction Mechanism ◽  
Small Polaron ◽  
Host Structure ◽  
Polaron Conduction ◽  
Small Polaron Conduction

We report Fe2WO6 to be an n-type thermoelectric (zT = 0.027 at 900 °C) with a small polaron conduction mechanism. Electrons reside as Fe2+ on the Fe3+ host structure, compensating oxygen vacancies that result from reduction in air above 650 °C.

scholarly journals Effects of Lattice Distortion, Polaron Conduction and Double-Exchange Interaction on the Physical Properties of Magnetoresistive Manganites and Cobaltites

1997 ◽  
Vol 474 ◽  
Author(s):  
N.-C. Yeh ◽  
R. P. Vasquez ◽  
J. Y. T. Wei ◽  
C-C. Fu ◽  
G. Beach ◽  
...  
Keyword(s):  
Physical Properties ◽  
Exchange Interaction ◽  
Electrical Transport ◽  
Colossal Magnetoresistance ◽  
Lattice Distortion ◽  
Double Exchange ◽  
Epitaxial Films ◽  
Strong Electron ◽  
Double Exchange Interaction ◽  
Polaron Conduction

ABSTRACTThe relevance of lattice distortion, polaron conduction, and double-exchange interaction to the occurrence of colossal magnetoresistance (CMR) is investigated by comparing the physical properties of magnetoresistive manganites and cobaltites. The samples studied in this work include epitaxial films and ceramics of manganites with both A- and B-site substitution, (La0.7Ca0.3MnO3, LaMn0.7 Ni0.3O3, LaMnO.5Ni0.5O3), as well as epitaxial films and ceramics of cobaltites (La0.5Ca0.5CoO3). The structural, chemical, electrical transport, magnetic, optical properties and tunneling spectroscopy are studied. Based on our experimental results, we conclude that both double-exchange interaction and strong electron-phonon coupling due to the Jahn-Teller effect are essential to the occurrence of CMR.

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