Description of the Colossal Magnetoresistance of La1.2Sr1.8Mn2O7 Based on Spin-Polaron and Orientation Conductivity Mechanisms in the Paramagnetic Temperature Region

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.

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POLARON AND SPIN-POLARON EFFECTS IN THE COLOSSAL MAGNETORESISTANCE

International Journal of Modern Physics B ◽

10.1142/s0217979299003969 ◽

1999 ◽

Vol 13 (29n31) ◽

pp. 3808-3814 ◽

Cited By ~ 1

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.

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Description of the Colossal Magnetoresistance of La1.2Sr1.8Mn2O7 Based on the Spin-Polaron Conduction Mechanism in the Ferromagnetic Temperature Range

Journal of Experimental and Theoretical Physics ◽

10.1134/s1063776120020120 ◽

2020 ◽

Vol 130 (4) ◽

pp. 543-548

Author(s):

S. A. Gudin ◽

N. I. Solin

Keyword(s):

Colossal Magnetoresistance ◽

Conduction Mechanism ◽

Spin Polaron ◽

Temperature Range ◽

Polaron Conduction

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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

Физика твердого тела ◽

10.21883/ftt.2018.06.45978.27m ◽

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.

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

Physics of the Solid State ◽

10.1134/s1063783418060112 ◽

2018 ◽

Vol 60 (6) ◽

pp. 1078-1081 ◽

Cited By ~ 2

Author(s):

S. A. Gudin ◽

N. I. Solin ◽

N. N. Gapontseva

Keyword(s):

Colossal Magnetoresistance ◽

Conduction Mechanism ◽

Spin Polaron ◽

Polaron Conduction

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The Effect of Reducing Time on the Magnetoresistance of Manganite La0.67Sr0.20Cu0.10□0.03MnO3at a Temperature of 30°C

Journal of Nanomaterials ◽

10.1155/2012/426037 ◽

2012 ◽

Vol 2012 ◽

pp. 1-5

Author(s):

Hongwei Zhao ◽

Lichun Hu ◽

Zhanxin Zhang

Keyword(s):

Magnetic Field ◽

Magnetic Properties ◽

Temperature Region ◽

Colossal Magnetoresistance ◽

Cation Vacancy ◽

Sol Gel ◽

Hydrogen Atmosphere ◽

Argon Atmosphere ◽

Parent Materials ◽

Electrical And Magnetic Properties

La0.67Sr0.20Cu0.10□0.03MnO3(“□” representing cation vacancy) polycrystalline manganite powder was synthesized by sol-gel method, which we used as parent materials. After reduced in hydrogen atmosphere for 30 and 60 minutes at a temperature of 400°C, the series bulk samples were obtained by sintering in argon atmosphere for 12 hours at 1100°C. The structure, electrical and magnetic properties, and colossal magnetoresistance of samples were researched in detail. Experiment results indicate that under an applied magnetic field of 1.8 T, the two bulk samples sintered in Ar atmosphere for 12 hours at 1100°C, with the powder reduced for 30 and 60 minutes in 400°C hydrogen atmosphere for La0.67Sr0.20Cu0.10□0.03MnO3parent powders, respectively, have the stable MR (11.0 ± 0.3)% and (10.0 ± 0.5)% in temperature region from 270 K to 330 K. this is important for the potential application of this kind of magnetoresistance materials.

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Аномальное изменение размера спинового полярона в парамагнитной области температур в La-=SUB=-1.2-=/SUB=-Sr-=SUB=-1.8-=/SUB=-Mn-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=-

Физика твердого тела ◽

10.21883/ftt.2021.12.51653.31s ◽

2021 ◽

Vol 63 (12) ◽

pp. 1978

Author(s):

С.А. Гудин

Keyword(s):

Magnetic Field ◽

Colossal Magnetoresistance ◽

Double Perovskite ◽

Peak Height ◽

Temperature Curve ◽

Linear Size ◽

Spin Polaron ◽

Anomalous Temperature ◽

Increasing Temperature ◽

The Magnetic Field

In this work, we continued the study of the magnetic and electrical properties of the double perovskite La1.2Sr1.8Mn2O7, which has a colossal magnetoresistance in excess of 1200 near the Curie temperature. It is shown that the colossal magnetoresistance observed in La1.2Sr1.8Mn2O7 is well described on the basis of the “orientational” and “spin-polaron” conduction mechanisms. It was found in the work that in the absence of a magnetic field, the linear size of the spin polaron decreases with increasing temperature in the ferromagnetic region, and upon the transition of manganite to the paramagnetic state, the linear size begins to increase, reaching a maximum at 180 K. At temperatures exceeding 180 K, an anomalous temperature change the size of the spin polaron disappears. In the absence of a magnetic field, the detected peak on the temperature curve of the change in the size of the spin polaron is maximal; with the inclusion of the magnetic field, the peak height decreases. Mechanisms are proposed to explain this anomalous temperature behavior of the spin polaron size.

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