Development of pulsed magnetic field and study of magnetotransport properties of K-doped La1-xCax-yKyMnO3CMR materials

S Bhattacharya, S Pal, RK Mukherjee, BK Chaudhuri, S Neeleshwar, YY Chen, S Mollah, HD Yang

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Temperature-dependent magnetization, magnetoresistance and magneto-thermoelectric power of the K doped La1−xCax−yKyMnO3 type samples with x=0.3 and 0⩽y⩽0.15 has been studied. All the samples exhibit sharp metal–insulator transition (MIT) around Tp accompanied by a ferromagnetic (metallic) to paramagnetic (semiconducting) phase transition with a well-defined Curie temperature TC (almost equal to Tp). Doping of monovalent K in the divalent Ca site of La1−xCax−yKyMnO3 drives the system from a high resistivity regime with lower Tp to a lower resistivity regime with higher Tp. Systematic increase of Curie temperature with increase of K doing is observed from the magnetization measurement down to 5 K. Low temperature resistivity (ρ) and thermoelectric power (Seebeck coefficient, S) data well fit the relations ρ=ρ0+ρ2T2 and S=S0+S3/2T3/2+S4T4, respectively, signifying the importance of electron–magnon scattering process (ρ2T2 and S3/2T3/2 term). On the other hand, the high temperature (T>Tp upto 320 K) conductivity data satisfy the variable range hopping (VRH) model. For T>320 K small polaron hopping model is more appropriate than the VRH model. High temperature thermoelectric power (TEP) data also indicates the formation of thermally activated small polarons. Even with very small change of y, the density of states at the Fermi level N(EF) changes considerably. The magnetotransport properties have been measured under pulsed magnetic field of microsecond duration. The decay time of the magnetic pulse within the sample (ι) varies with field strength, which indicates that with change of magnetic field, ordering of the spin in the ferromagnetic regime changes.
Original languageEnglish
Pages (from-to)359-371
JournalJournal of Magnetism and Magnetic Materials
Volume269
Issue number3
DOIs
Publication statusPublished - 2004
MoE publication typeA1 Journal article-refereed

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Galvanomagnetic effects
Thermoelectric power
Magnetic fields
electrical resistivity
Curie temperature
magnetic fields
Magnetization
magnetization
polarons
Seebeck effect
Gene Conversion
Polarons
Temperature
Seebeck coefficient
field strength
Magnetoresistance
Fermi level
conductivity
Phase transitions
Doping (additives)

Cite this

Bhattacharya, S ; Pal, S ; Mukherjee, RK ; Chaudhuri, BK ; Neeleshwar, S ; Chen, YY ; Mollah, S ; Yang, HD. / Development of pulsed magnetic field and study of magnetotransport properties of K-doped La1-xCax-yKyMnO3CMR materials. In: Journal of Magnetism and Magnetic Materials. 2004 ; Vol. 269, No. 3. pp. 359-371.
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title = "Development of pulsed magnetic field and study of magnetotransport properties of K-doped La1-xCax-yKyMnO3CMR materials",
abstract = "Temperature-dependent magnetization, magnetoresistance and magneto-thermoelectric power of the K doped La1−xCax−yKyMnO3 type samples with x=0.3 and 0⩽y⩽0.15 has been studied. All the samples exhibit sharp metal–insulator transition (MIT) around Tp accompanied by a ferromagnetic (metallic) to paramagnetic (semiconducting) phase transition with a well-defined Curie temperature TC (almost equal to Tp). Doping of monovalent K in the divalent Ca site of La1−xCax−yKyMnO3 drives the system from a high resistivity regime with lower Tp to a lower resistivity regime with higher Tp. Systematic increase of Curie temperature with increase of K doing is observed from the magnetization measurement down to 5 K. Low temperature resistivity (ρ) and thermoelectric power (Seebeck coefficient, S) data well fit the relations ρ=ρ0+ρ2T2 and S=S0+S3/2T3/2+S4T4, respectively, signifying the importance of electron–magnon scattering process (ρ2T2 and S3/2T3/2 term). On the other hand, the high temperature (T>Tp upto 320 K) conductivity data satisfy the variable range hopping (VRH) model. For T>320 K small polaron hopping model is more appropriate than the VRH model. High temperature thermoelectric power (TEP) data also indicates the formation of thermally activated small polarons. Even with very small change of y, the density of states at the Fermi level N(EF) changes considerably. The magnetotransport properties have been measured under pulsed magnetic field of microsecond duration. The decay time of the magnetic pulse within the sample (ι) varies with field strength, which indicates that with change of magnetic field, ordering of the spin in the ferromagnetic regime changes.",
author = "S Bhattacharya and S Pal and RK Mukherjee and BK Chaudhuri and S Neeleshwar and YY Chen and S Mollah and HD Yang",
year = "2004",
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language = "English",
volume = "269",
pages = "359--371",
journal = "Journal of Magnetism and Magnetic Materials",
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Development of pulsed magnetic field and study of magnetotransport properties of K-doped La1-xCax-yKyMnO3CMR materials. / Bhattacharya, S; Pal, S; Mukherjee, RK; Chaudhuri, BK; Neeleshwar, S; Chen, YY; Mollah, S; Yang, HD.

In: Journal of Magnetism and Magnetic Materials, Vol. 269, No. 3, 2004, p. 359-371.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Development of pulsed magnetic field and study of magnetotransport properties of K-doped La1-xCax-yKyMnO3CMR materials

AU - Bhattacharya, S

AU - Pal, S

AU - Mukherjee, RK

AU - Chaudhuri, BK

AU - Neeleshwar, S

AU - Chen, YY

AU - Mollah, S

AU - Yang, HD

PY - 2004

Y1 - 2004

N2 - Temperature-dependent magnetization, magnetoresistance and magneto-thermoelectric power of the K doped La1−xCax−yKyMnO3 type samples with x=0.3 and 0⩽y⩽0.15 has been studied. All the samples exhibit sharp metal–insulator transition (MIT) around Tp accompanied by a ferromagnetic (metallic) to paramagnetic (semiconducting) phase transition with a well-defined Curie temperature TC (almost equal to Tp). Doping of monovalent K in the divalent Ca site of La1−xCax−yKyMnO3 drives the system from a high resistivity regime with lower Tp to a lower resistivity regime with higher Tp. Systematic increase of Curie temperature with increase of K doing is observed from the magnetization measurement down to 5 K. Low temperature resistivity (ρ) and thermoelectric power (Seebeck coefficient, S) data well fit the relations ρ=ρ0+ρ2T2 and S=S0+S3/2T3/2+S4T4, respectively, signifying the importance of electron–magnon scattering process (ρ2T2 and S3/2T3/2 term). On the other hand, the high temperature (T>Tp upto 320 K) conductivity data satisfy the variable range hopping (VRH) model. For T>320 K small polaron hopping model is more appropriate than the VRH model. High temperature thermoelectric power (TEP) data also indicates the formation of thermally activated small polarons. Even with very small change of y, the density of states at the Fermi level N(EF) changes considerably. The magnetotransport properties have been measured under pulsed magnetic field of microsecond duration. The decay time of the magnetic pulse within the sample (ι) varies with field strength, which indicates that with change of magnetic field, ordering of the spin in the ferromagnetic regime changes.

AB - Temperature-dependent magnetization, magnetoresistance and magneto-thermoelectric power of the K doped La1−xCax−yKyMnO3 type samples with x=0.3 and 0⩽y⩽0.15 has been studied. All the samples exhibit sharp metal–insulator transition (MIT) around Tp accompanied by a ferromagnetic (metallic) to paramagnetic (semiconducting) phase transition with a well-defined Curie temperature TC (almost equal to Tp). Doping of monovalent K in the divalent Ca site of La1−xCax−yKyMnO3 drives the system from a high resistivity regime with lower Tp to a lower resistivity regime with higher Tp. Systematic increase of Curie temperature with increase of K doing is observed from the magnetization measurement down to 5 K. Low temperature resistivity (ρ) and thermoelectric power (Seebeck coefficient, S) data well fit the relations ρ=ρ0+ρ2T2 and S=S0+S3/2T3/2+S4T4, respectively, signifying the importance of electron–magnon scattering process (ρ2T2 and S3/2T3/2 term). On the other hand, the high temperature (T>Tp upto 320 K) conductivity data satisfy the variable range hopping (VRH) model. For T>320 K small polaron hopping model is more appropriate than the VRH model. High temperature thermoelectric power (TEP) data also indicates the formation of thermally activated small polarons. Even with very small change of y, the density of states at the Fermi level N(EF) changes considerably. The magnetotransport properties have been measured under pulsed magnetic field of microsecond duration. The decay time of the magnetic pulse within the sample (ι) varies with field strength, which indicates that with change of magnetic field, ordering of the spin in the ferromagnetic regime changes.

U2 - 10.1016/S0304-8853(03)00632-2

DO - 10.1016/S0304-8853(03)00632-2

M3 - Article

VL - 269

SP - 359

EP - 371

JO - Journal of Magnetism and Magnetic Materials

JF - Journal of Magnetism and Magnetic Materials

SN - 0304-8853

IS - 3

ER -