Parimi, Patanjali; Zhai, Zhiyong; Hakim, Nazih; Kusko, Christian; Sridhar, Srinivas; Amerahl, Udo; Vietkine, A; Revcolevschi, A
Charge Polarization Dynamics of Spin-Ladder and Spin-Chain Sr-Cu-O Cuprates. Proceedings Article
In: APS Meeting Abstracts, 2000.
@inproceedings{parimi2000charge,
title = {Charge Polarization Dynamics of Spin-Ladder and Spin-Chain Sr-Cu-O Cuprates.},
author = {Patanjali Parimi and Zhiyong Zhai and Nazih Hakim and Christian Kusko and Srinivas Sridhar and Udo Amerahl and A Vietkine and A Revcolevschi},
year = {2000},
date = {2000-01-01},
booktitle = {APS Meeting Abstracts},
abstract = {Single crystals of spin-ladder and spin-chain cuprates, Sr-Cu-O, revealed novel features in the temperature dependence of microwave dielectric susceptibility, ε= ε'+ iε", carried out in a highly sensitive a superconducting microwave cavity. The results show new dynamic phenomena due to dielectric relaxation with time scales corresponding to GHz frequency range. For spin-ladder Sr_14-xCa_xCu_24O_41 with x= 0 we have observed loss peak with a pronounced frequency dependence in the ε"(omega, T) response around 200K accompanied by a rapid decrease in ε'(omega, T). The frequency dependence of this phenomenon can be understood by considering a complex dielectric constant ε= ε 0/(1-i omega tau). Doping dependence of ε (omega, T) for x= 2, 8, 11.5 showed a shift in the peak to lower temperatures. The microscopic origin of this phenomenon can be understood by comparing the ε (omega, T) of …},
keywords = {Collective Excitations, Magnetism, Superconductivity},
pubstate = {published},
tppubtype = {inproceedings}
}
Single crystals of spin-ladder and spin-chain cuprates, Sr-Cu-O, revealed novel features in the temperature dependence of microwave dielectric susceptibility, ε= ε'+ iε", carried out in a highly sensitive a superconducting microwave cavity. The results show new dynamic phenomena due to dielectric relaxation with time scales corresponding to GHz frequency range. For spin-ladder Sr_14-xCa_xCu_24O_41 with x= 0 we have observed loss peak with a pronounced frequency dependence in the ε"(omega, T) response around 200K accompanied by a rapid decrease in ε'(omega, T). The frequency dependence of this phenomenon can be understood by considering a complex dielectric constant ε= ε 0/(1-i omega tau). Doping dependence of ε (omega, T) for x= 2, 8, 11.5 showed a shift in the peak to lower temperatures. The microscopic origin of this phenomenon can be understood by comparing the ε (omega, T) of …
Patanjali, PV; Theule, P; Zhai, Z; Hakim, N; Sridhar, S; Suryanarayanan, R; Apostu, M; Dhalenne, G; Revcolevschi, A
High-frequency magnetoimpedance of double perovskite La 1.2 Sr 1.8 Mn 2 O 7: Secondary transitions at high temperatures Journal Article
In: Physical Review B, vol. 60, no. 13, pp. 9268, 1999.
@article{patanjali1999high,
title = {High-frequency magnetoimpedance of double perovskite La 1.2 Sr 1.8 Mn 2 O 7: Secondary transitions at high temperatures},
author = {PV Patanjali and P Theule and Z Zhai and N Hakim and S Sridhar and R Suryanarayanan and M Apostu and G Dhalenne and A Revcolevschi},
year = {1999},
date = {1999-01-01},
journal = {Physical Review B},
volume = {60},
number = {13},
pages = {9268},
publisher = {American Physical Society},
abstract = {The nonlinear dependence on applied ac field
(
b
ω
)
or current
(
i
ω
)
of the microwave (ac) impedance
R
ω
+
i
X
ω
of both short and long Josephson junctions is calculated under a variety of excitation conditions. The dependence on the junction width is studied, for both field symmetric (current antisymmetric) and field antisymmetric (current symmetric) excitation configurations. The resistance shows steplike features every time a fluxon (soliton) enters the junction, with a corresponding phase slip seen in the reactance. For finite widths the interference of fluxons leads to some interesting effects which are described. Many of these calculated results are observed in microwave impedance measurements on intrinsic and fabricated Josephson junctions in the high temperature superconductors. When a dc field
(
b
dc
)
or current
(
i
dc
)
is applied, interesting phase locking effects are observed in the ac impedance
Z
ω
.
In particular an almost periodic dependence on the dc bias is seen similar to that observed in microwave experiments at very low dc field bias. These results are generic to all systems with a
cos
(
φ
)
potential in the overdamped limit and subjected to an ac drive.},
keywords = {Magnetism, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
The nonlinear dependence on applied ac field
(
b
ω
)
or current
(
i
ω
)
of the microwave (ac) impedance
R
ω
+
i
X
ω
of both short and long Josephson junctions is calculated under a variety of excitation conditions. The dependence on the junction width is studied, for both field symmetric (current antisymmetric) and field antisymmetric (current symmetric) excitation configurations. The resistance shows steplike features every time a fluxon (soliton) enters the junction, with a corresponding phase slip seen in the reactance. For finite widths the interference of fluxons leads to some interesting effects which are described. Many of these calculated results are observed in microwave impedance measurements on intrinsic and fabricated Josephson junctions in the high temperature superconductors. When a dc field
(
b
dc
)
or current
(
i
dc
)
is applied, interesting phase locking effects are observed in the ac impedance
Z
ω
.
In particular an almost periodic dependence on the dc bias is seen similar to that observed in microwave experiments at very low dc field bias. These results are generic to all systems with a
cos
(
φ
)
potential in the overdamped limit and subjected to an ac drive.
Hakim, N; Zhai, Z; Kusko, C; Parimi, PV; Cheong, SW; Sridhar, S
Polarization Dynamics in La 5/3 Sr 1/3 NiO 4 Journal Article
In: MRS Online Proceedings Library Archive, vol. 602, 1999.
@article{hakim1999polarization,
title = {Polarization Dynamics in La 5/3 Sr 1/3 NiO 4},
author = {N Hakim and Z Zhai and C Kusko and PV Parimi and SW Cheong and S Sridhar},
year = {1999},
date = {1999-01-01},
journal = {MRS Online Proceedings Library Archive},
volume = {602},
publisher = {Cambridge University Press},
keywords = {Magnetism},
pubstate = {published},
tppubtype = {article}
}
Parimi, PV; Srikanth, H; Bailleul, M; Sridhar, S; Suryanarayanan, R; Pinsard, L; Revcolevschi, A
rf Susceptibility of La 1- x Sr x MnO 3 Single Crystals: Magnetic Signatures of Structural Changes Journal Article
In: MRS Online Proceedings Library Archive, vol. 602, 1999.
@article{parimi1999rf,
title = {rf Susceptibility of La 1- x Sr x MnO 3 Single Crystals: Magnetic Signatures of Structural Changes},
author = {PV Parimi and H Srikanth and M Bailleul and S Sridhar and R Suryanarayanan and L Pinsard and A Revcolevschi},
year = {1999},
date = {1999-01-01},
journal = {MRS Online Proceedings Library Archive},
volume = {602},
publisher = {Cambridge University Press},
keywords = {Magnetism, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Choudhury, Durga P; Derov, John S; Sridhar, S
Measurement and modeling of nonlinear microwave response of high temperature superconductors Proceedings Article
In: APS March Meeting Abstracts, 1998.
@inproceedings{choudhury1998measurement,
title = {Measurement and modeling of nonlinear microwave response of high temperature superconductors},
author = {Durga P Choudhury and John S Derov and S Sridhar},
year = {1998},
date = {1998-01-01},
booktitle = {APS March Meeting Abstracts},
abstract = {Results of experiments carried out to probe the nonlinear microwave response of epitaxial thin film YBa_2Cu_3O_7-delta resonators under a variety of conditions, including the application of a very small DC magnetic field is described. The suspended geometry used in the setup has no superconducting ground planes and is thus highly sensitive to low applied fields which was parallel to the c-axis of the film. Measurement of harmonic power generation and intermodulation products as a function of temperature and applied field show several novel features in the region of parameter space where< A HREF= http://sagar. physics. neu. edu/preprints. html> earlier measurements of surface resistance(R_S) have shown a marked decrease in nonlinearity and R_S. The observed results will be discussed in the context of the Critical State and other models of vortex dynamics in HTSC materials. A finite element numerical …},
keywords = {Magnetism, Superconductivity},
pubstate = {published},
tppubtype = {inproceedings}
}
Results of experiments carried out to probe the nonlinear microwave response of epitaxial thin film YBa_2Cu_3O_7-delta resonators under a variety of conditions, including the application of a very small DC magnetic field is described. The suspended geometry used in the setup has no superconducting ground planes and is thus highly sensitive to low applied fields which was parallel to the c-axis of the film. Measurement of harmonic power generation and intermodulation products as a function of temperature and applied field show several novel features in the region of parameter space where< A HREF= http://sagar. physics. neu. edu/preprints. html> earlier measurements of surface resistance(R_S) have shown a marked decrease in nonlinearity and R_S. The observed results will be discussed in the context of the Critical State and other models of vortex dynamics in HTSC materials. A finite element numerical …
Srikanth, H; Revcolevschi, B; Sridhar, S; Pinsard, L; Revcolvschi, A
High frequency magneto-electrodynamics of La $$sub 1 $$minus$$ x$$ Sr $$sub x$$ MnO $$sub 3$$ single crystals Technical Report
Materials Research Society, Warrendale, PA (United States) 1998.
@techreport{srikanth1998high,
title = {High frequency magneto-electrodynamics of La $$sub 1 $$minus$$ x$$ Sr $$sub x$$ MnO $$sub 3$$ single crystals},
author = {H Srikanth and B Revcolevschi and S Sridhar and L Pinsard and A Revcolvschi},
year = {1998},
date = {1998-01-01},
institution = {Materials Research Society, Warrendale, PA (United States)},
keywords = {Magnetism},
pubstate = {published},
tppubtype = {techreport}
}
Srikanth, H; Revcolevschi, B; Choudhury, DP; Sridhar, S; Pinsard, L; Revcolevschi, A
High frequency electrodynamics of La_1-xSr_xMnO3 single crystals Proceedings Article
In: APS March Meeting Abstracts, 1998.
@inproceedings{srikanth1998highb,
title = {High frequency electrodynamics of La_1-xSr_xMnO3 single crystals},
author = {H Srikanth and B Revcolevschi and DP Choudhury and S Sridhar and L Pinsard and A Revcolevschi},
year = {1998},
date = {1998-01-01},
booktitle = {APS March Meeting Abstracts},
abstract = {The electrodynamic response of La_1-xSr_xMnO 3 single crsytals at radio-frequencies (RF) reveal a variety of features associated with the structural, magnetic and electronic properties of the system. Insulating and metallic samples with varying Sr content were investigated using a very sensitive RF inductance technique operating at 3 MHz. A colossal frequency shift is observed at the ferromagnetic (FM) transition and sharp changes are seen at the orthorhombic structural transitions associated with Jahn-Teller distortions. In addition, our experiments show rich structure in the different phases which are not clearly observed in conventional DC magnetization and transport experiments. A phase diagram with the characteristic temperature and field scales derived from our high frequency measurements is obtained. Microwave surface impedance results at 10 GHz on the metallic samples will also be presented. Overall …},
keywords = {Magnetism, Superconductivity},
pubstate = {published},
tppubtype = {inproceedings}
}
The electrodynamic response of La_1-xSr_xMnO 3 single crsytals at radio-frequencies (RF) reveal a variety of features associated with the structural, magnetic and electronic properties of the system. Insulating and metallic samples with varying Sr content were investigated using a very sensitive RF inductance technique operating at 3 MHz. A colossal frequency shift is observed at the ferromagnetic (FM) transition and sharp changes are seen at the orthorhombic structural transitions associated with Jahn-Teller distortions. In addition, our experiments show rich structure in the different phases which are not clearly observed in conventional DC magnetization and transport experiments. A phase diagram with the characteristic temperature and field scales derived from our high frequency measurements is obtained. Microwave surface impedance results at 10 GHz on the metallic samples will also be presented. Overall …
Srikanth, H; Revcolevschi, B; Sridhar, S; Pinsard, L; Revcolevschi, A
High Frequency Magneto-Electrodynamics of La 1-x Sr x MnO 3 Single Crystals Journal Article
In: MRS Online Proceedings Library Archive, vol. 494, 1997.
@article{srikanth1997high,
title = {High Frequency Magneto-Electrodynamics of La 1-x Sr x MnO 3 Single Crystals},
author = {H Srikanth and B Revcolevschi and S Sridhar and L Pinsard and A Revcolevschi},
year = {1997},
date = {1997-01-01},
journal = {MRS Online Proceedings Library Archive},
volume = {494},
publisher = {Cambridge University Press},
keywords = {Magnetism},
pubstate = {published},
tppubtype = {article}
}
Srikanth, H; Revcolevschi, B; Sridhar, S; Pinsard, L; Revcolevschi, A
Evidence for Short-range Magnetic Order and Spin-gap? The broad peaks between 400 cm Journal Article
In: 0000.
@article{srikanthevidence,
title = {Evidence for Short-range Magnetic Order and Spin-gap? The broad peaks between 400 cm},
author = {H Srikanth and B Revcolevschi and S Sridhar and L Pinsard and A Revcolevschi},
keywords = {Magnetism},
pubstate = {published},
tppubtype = {article}
}
Srikanth, H; Revcolevschi, B; Sridhar, S; Pinsard, L; Revcolevschi, A
HIGH FREQUENCY MAGNETO-ELECTRODYNAMICS OF Lal. xSrxMnO 3 SINGLE Journal Article
In: 0000.
@article{srikanthhigh,
title = {HIGH FREQUENCY MAGNETO-ELECTRODYNAMICS OF Lal. xSrxMnO 3 SINGLE},
author = {H Srikanth and B Revcolevschi and S Sridhar and L Pinsard and A Revcolevschi},
abstract = {The radio frequency (RF) response of La1-xSrxMnO3 single crystals reveal a variety of features associated with the structural, electronic and magnetic properties of the system. The resonance technique operating at ∼ 4 MHz employed in this study is sensitive to small changes in both the magnetic susceptibility and resistivity of the samples. Very sharp changes in frequency are observed at the ferromagnetic (FM) and structural phase transitions in both the metallic (x = 0.175) and insulating (0.125) crystals studied.
In addition to the known transitions identified as FM and orthorhombic distortions, our experiments show rich structures which are not observed in conventional DC magnetization and transport experiments. Our results demonstrate that RF experiments are ideally suited to investigate the complex phase diagram in the manganites.
The colossal frequency change that we observe at the FM transition in the La1-xSrxMnO3 crystals is indicative of the enormous potential for using these materials in high frequency switching applications.},
keywords = {Magnetism},
pubstate = {published},
tppubtype = {article}
}
The radio frequency (RF) response of La1-xSrxMnO3 single crystals reveal a variety of features associated with the structural, electronic and magnetic properties of the system. The resonance technique operating at ∼ 4 MHz employed in this study is sensitive to small changes in both the magnetic susceptibility and resistivity of the samples. Very sharp changes in frequency are observed at the ferromagnetic (FM) and structural phase transitions in both the metallic (x = 0.175) and insulating (0.125) crystals studied.
In addition to the known transitions identified as FM and orthorhombic distortions, our experiments show rich structures which are not observed in conventional DC magnetization and transport experiments. Our results demonstrate that RF experiments are ideally suited to investigate the complex phase diagram in the manganites.
The colossal frequency change that we observe at the FM transition in the La1-xSrxMnO3 crystals is indicative of the enormous potential for using these materials in high frequency switching applications.
