The high temperature superconductors which were discovered in 1986 still continue to pose major challenges to scientists. Not only is the mechanism for superconductivity not known, but the nature of the superconducting state and the motion of vortices continue to be debated intensely. We study the microwave response of superconductors, both for understanding the nature of superconductivity, the dynamics of vortices and for practical applications in microwave devices.

The principal areas of our research are:

  • Fundamental measurements and analysis of the penetration depth and surface impedance of superconductors, with a view to understanding the pairing state, the quasiparticle spectrum and the gap parameter
  • Vortex dynamics at high (rf and microwave) frequencies to obtain quantiative measurements of parameters such as pinning force constants, vortex viscosity, critical fields, melting and vortex glass transitions
  • Flux penetration and critical state dynamics
  • Josephson type nonlinear phenomena at microwave frequencies
  • Development of novel measurement techniques, such as the “hot finger” cavity method to measure surface impedance, tunnel diode technique of measuring penetration depth, patterned film structures to study vortex dynamics, modulated microwave absorption

The materials we study are the cuprate High Tc superconductors, borocarbides, and organic superconductors.

Our work in Superconductivity is supported by:

  • National Science Foundation
  • Division of Materials Research and Division of Electrical and Communications Systems, Rome Laboratory, Hanscom AFB (an AFOSR lab)

Related Publications

Choudhury, Durga P; Derov, John S; Sridhar, S

Harmonic generation from YBa2Cu3O7- $delta$ microwave resonators Journal Article

In: Measurement, 2008.

Tags: Superconductivity

Choudhury, Durga P; Sridhar, S

Superconducting microwave technology Journal Article

In: Encyclopedia of RF and Microwave Engineering, 2005.

Abstract | Tags: Superconductivity

Bishop, Alan R; Srinivas, Sridhar; others,

Intrinsic Multiscale Structure and Dynamics in Complex Electronic Oxides, Proceedings of the Workshop Miscellaneous

2003.

Abstract | Tags: Superconductivity

Sridhar, S; Shenoy, SR; for Physics, Abdus Salam International Centre Theoretical; Bishop, AR

Proceedings of the Workshop: Intrinsic Multiscale Structure and Dynamics in Complex Electronic Oxides (Intrinsic Multiscale Structure and Dynamics in Complex Electronic Oxides) Miscellaneous

2003.

Tags: Superconductivity

Sridhar, S; Kusko, C; Zhai, Z

Is There a Narrow Conductivity Mode in the Superconducting Oxides? Incollection

In: Intrinsic Multiscale Structure And Dynamics In Complex Electronic Oxides, pp. 69–83, 2003.

Abstract | Tags: Superconductivity

Hakim, Nazih; Kusko, Christian; Sridhar, Srinivas

Microwave and Radio Frequency Response of MgB_2. Inproceedings

In: APS Meeting Abstracts, 2003.

Abstract | Tags: Superconductivity

Hakim, Nazih; Parimi, Patanjali; Kusko, Christian; Sridhar, Srinivas

Microwave and Radio Frequency, RF, Measurements on Superconducting MgB_2. Inproceedings

In: APS Meeting Abstracts, 2002.

Abstract | Tags: Superconductivity

Kusko, C; Zhai, Z; Hakim, N; Markiewicz, RS; Sridhar, S; Colson, D; Viallet-Guillen, V; Forget, A; Nefyodov, Yu A; Trunin, MR; others,

Anomalous microwave conductivity due to collective transport in the pseudogap state of cuprate superconductors Journal Article

In: Physical Review B, 65 (13), pp. 132501, 2002.

Abstract | Tags: Superconductivity

Bishop, AR; Shenoy, SR; Sridhar, S

Intrinsic Multiscale Structure and Dynamics in Complex Electronic Oxides Inproceedings

In: World Scientific Singapore Proceedings of the Workshop ICTP, Trieste, Italy 2002.

Abstract | Tags: Superconductivity

Hakim, N; Kusko, C; Sridhar, S; Soukiassian, A; Zeng, XH; Xi, XX

The superconducting gap of in situ MgB 2 thin films by microwave surface impedance measurements Journal Article

In: Applied Physics Letters, 81 (19), pp. 3603–3605, 2002.

Tags: Superconductivity

Sridhar, S

Microwave Properties of Superconducting MgB_2 Inproceedings

In: APS Meeting Abstracts, 2002.

Tags: Superconductivity

Hakim, Nazih; Parimi, Patanjali V; Nyeanchi, Emmanuel; Sridhar, Srinivas; Chou, F-C

Microwave properties of superconducting and insulating La_2-xSr_xCuO_4 Inproceedings

In: APS Meeting Abstracts, 2001.

Abstract | Tags: Superconductivity

Kusko, C; Zhai, Z; Hakim, N; Sridhar, S

Signature of the pseudogap state in microwave transport in cuprate superconductors Inproceedings

In: APS Meeting Abstracts, 2001.

Abstract | Tags: Superconductivity

Zhai, Z; Kusko, C; Sridhar, S

Anomalous microwave scattering rate in cuprate superconductors Inproceedings

In: APS Meeting Abstracts, 2001.

Abstract | Tags: Superconductivity

Kusko, C; Zhai, Z; Markiewicz, RS; Sridhar, S

Anomalous scattering rate and microwave absorption in Bi₂Sr₂CaCu₂O₈₊ $delta$ and Y Ba₂Cu₃O₇₋ $delta$ Journal Article

In: 2001.

Tags: Superconductivity

Parimi, Patanjali; Hakim, Nazih; Sridhar, Srinivas

Dielectric transitions driven by local lattice distortions in perovskite oxides, YBa2 Cu3 O_6. 0, La_2CuO4 and La_5/3Sr_1/3NiO_4. Inproceedings

In: APS March Meeting Abstracts, 2001.

Abstract | Tags: Superconductivity

Hakim, N; Parimi, PV; Kusko, C; Sridhar, S; Canfield, Paul C; Bud’ko, Sergey L; Finnemore, Douglas K

Microwave properties of superconducting MgB 2 Journal Article

In: Applied Physics Letters, 78 (26), pp. 4160–4162, 2001.

Tags: Superconductivity

Zhai, Z; Parimi, PV; Sokoloff, JB; Sridhar, S; Erb, A

Onset of dielectric modes at 110 K and 60 K due to local lattice distortions in nonsuperconducting YBa 2 Cu 3 O 6.0 crystals Journal Article

In: Physical Review B, 63 (9), pp. 092508, 2001.

Abstract | Tags: Superconductivity

Dasgupta, T; Derov, JS; Sridhar, S

Computer-aided modeling of superconducting striplines with ground planes using critical state models Journal Article

In: Journal of Applied Physics, 90 (6), pp. 2915–2918, 2001.

Abstract | Tags: Superconductivity

PARIMI, PV; SRIKANTH, H; BAILLEUL, M; SRIDHAR, S

R. SURYANARAYANAN, L. PINSARD and A. REVCOLEVSCHI. Journal Article

In: Tc, 200 (250), pp. 300, 2001.

Abstract | Tags: Superconductivity

Kusko, C; Zhai, Z; Markiewicz, RS; Sridhar, S

Anomalous Scattering Rate and Microwave Absorption in Bi2Sr2CaCu2O8+ $delta$ and YBa2Cu3O7- $delta$ Journal Article

In: Journal of superconductivity, 14 (1), pp. 81–84, 2001.

Tags: Superconductivity

Dresselhaus, MS; Oates, D; Sridhar, S

Studies of High-T sub c Superconducting Films for High-Power Microwave Applications Technical Report

DTIC Document 2001.

Abstract | Tags: Superconductivity

Parimi, PV; Hakim, N; Chou, FC; Cheong, SW; Sridhar, S

Dielectric signatures of lattice instabilities at 32K and 245K in $ La_ $$2-y$$ Sr_ $$y$$ MO_ $$4+ x$$ $(M= Cu, Ni) Cuprates and Nickelates Journal Article

In: arXiv preprint cond-mat/0108342, 2001.

Tags: Superconductivity

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. Inproceedings

In: APS Meeting Abstracts, 2000.

Abstract | Tags: Collective Excitations, Magnetism, Superconductivity

Xin, H; Oates, DE; Sridhar, S; Dresselhaus, G; Dresselhaus, MS

RAPID COMMUNICATIONS-Superfluidity and superconductivity-Observation of individual Josephson vortices in YBa2Cu3O7-d bicrystal grain-boundary junctions Journal Article

In: Physical Review-Section B-Condensed Matter, 61 (22), pp. R14952, 2000.

Tags: Superconductivity

Zhai, Z; Kusko, C; Hakim, N; Sridhar, S; Revcolevschi, A; Vietkine, A

Precision microwave dielectric and magnetic susceptibility measurements of correlated electronic materials using superconducting cavities Journal Article

In: Review of Scientific Instruments, 71 (8), pp. 3151–3160, 2000.

Abstract | Tags: Superconductivity

Xin, Hao; Oates, DE; Sridhar, S; Dresselhaus, G; Dresselhaus, MS

Observation of individual Josephson vortices in YBa 2 Cu 3 O 7- $delta$ bicrystal grain-boundary junctions Journal Article

In: Physical Review B, 61 (22), pp. R14952, 2000.

Tags: Superconductivity

Zhai, Z; Parimi, Patanjali V; Sridhar, S

Erratum: Nonlinear microwave impedance of short and long Josephson junctions [Phys. Rev. B 59, 9573 (1999)] Journal Article

In: Physical Review B, 62 (17), pp. 11888, 2000.

Abstract | Tags: Superconductivity

Sridhar, S; Giannakopoulos, AE; Suresh, S

STRUCTURAL, MECHANICAL, THERMODYNAMIC, AND OPTICAL PROPERTIES OF CONDENSED MATTER (PACS 61-68, 78)-Mechanical and electrical responses of piezoelectric solids to conical indentation Journal Article

In: Journal of Applied Physics, 87 (12), pp. 8451–8456, 2000.

Tags: Superconductivity

Sridhar, S; Zhai, Z

Non-quasiparticle microwave absorption in Bi2Sr2CaCu2O8+ $delta$ Journal Article

In: Physica C: Superconductivity, 341 , pp. 2057–2060, 2000.

Tags: Superconductivity

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, 602 , 1999.

Tags: Magnetism, Superconductivity

Dasgupta, T; Choudhury, Durga P; Sridhar, S

Modeling nonlinearity and hysteresis due to critical-state flux penetration in hard superconductors Journal Article

In: arXiv preprint cond-mat/9905063, 1999.

Abstract | Tags: Superconductivity

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, 60 (13), pp. 9268, 1999.

Abstract | Tags: Magnetism, Superconductivity

Zhai, Z; Patanjali, PV; Hakim, N; Sokoloff, JB; Sridhar, S; Ammerahl, U; Vietkine, A; Revcolevschi, A

Observation of spin freezing and relaxation at microwave frequencies in the spin ladder compound $ Sr_ $$14-x$$ Ca_ $$x$$ Cu_ $$24$$ O_ $$41$$ $ Journal Article

In: arXiv preprint cond-mat/9903198, 1999.

Tags: Superconductivity

Sridhar, S; Zhai, Z; Erb, A

Microwave Absorption Peaks: Signatures of Spin Dynamics in Cuprates Journal Article

In: arXiv preprint cond-mat/9906053, 1999.

Abstract | Tags: Superconductivity

Choudhury, Durga P; Derov, John S; Sridhar, S

Harmonic generation from YBCO microwave resonators Journal Article

In: arXiv preprint cond-mat/9904080, 1999.

Abstract | Tags: Superconductivity

Zhai, Z; Parimi, Patanjali V; Sridhar, S

Nonlinear microwave impedance of short and long Josephson junctions Journal Article

In: Physical Review B, 59 (14), pp. 9573, 1999.

Tags: Superconductivity

Kidambi, V; Zhai, Z; Srikanth, H; Sridhar, S; Erb, A; Li, Qiang

Vortex response of YBCO and BSCCO single crystals from RF experiments Inproceedings

In: APS March Meeting Abstracts, 1998.

Abstract | Tags: Superconductivity

Srikanth, H; Revcolevschi, B; Choudhury, DP; Sridhar, S; Pinsard, L; Revcolevschi, A

High frequency electrodynamics of La_1-xSr_xMnO3 single crystals Inproceedings

In: APS March Meeting Abstracts, 1998.

Abstract | Tags: Magnetism, Superconductivity

Srikanth, H; Zhai, Z; Sridhar, S; Erb, A; Walker, E

Systematics of two-component superconductivity in YBa 2 Cu 3 O 6.95 from microwave measurements of high-quality single crystals Journal Article

In: Physical Review B, 57 (13), pp. 7986, 1998.

Abstract | Tags: Superconductivity

Zhai, Z; Srikanth, H; Sridhar, S; Erb, A

Microwave properties of YBCO and other cuprate single crystals Inproceedings

In: APS March Meeting Abstracts, 1998.

Abstract | Tags: Superconductivity

Bansil, A; Markiewicz, B; Sridhar, S; Liebenberg, D

Spectroscopies in novel superconductors-Preface Miscellaneous

1998.

Tags: Superconductivity

Srikanth, H; Zhai, Z; Sridhar, S; Erb, A

Microwave properties of YBCO crystals grown in BaZrO3 crucibles: influence of c-axis currents Journal Article

In: Journal of Physics and Chemistry of Solids, 59 (10-12), pp. 2105–2109, 1998.

Abstract | Tags: Superconductivity

Choudhury, Durga P; Srikanth, H; Sridhar, S; Canfield, PC

Magnetoelectrodynamics at high frequencies in the antiferromagnetic and superconducting states of DyNi 2 B 2 C Journal Article

In: Physical Review B, 58 (21), pp. 14490, 1998.

Abstract | Tags: Superconductivity

Choudhury, Durga P; Derov, John S; Sridhar, S

Measurement and modeling of nonlinear microwave response of high temperature superconductors Inproceedings

In: APS March Meeting Abstracts, 1998.

Abstract | Tags: Magnetism, Superconductivity

Srikanth, H; Willemson, BA; Jacobs, T; Sridhar, S

New Features in the Microwave Response of YBa 2 Cu 3 O 6.95 Crystals: Evidence for a Multicomponent Order Parameter Journal Article

In: arXiv preprint cond-mat/9610032, 1997.

Abstract | Tags: Superconductivity

Eskildsen, MR; Gammel, PL; Barber, BP; Yaron, U; Ramirez, AP; Huse, DA; Bishop, DJ; Bolle, C; Lieber, CM; Oxx, S; others,

Observation of a field-driven structural phase transition in the flux line lattice in ErNi 2 B 2 C Journal Article

In: Physical review letters, 78 (10), pp. 1968, 1997.

Tags: Superconductivity

Srikanth, H; Willemsen, Balam A; Jacobs, T; Sridhar, S; Erb, A; Walker, E; Flükiger, R

Microwave response of YBa 2 Cu 3 O 6.95 crystals: Evidence for a multicomponent order parameter Journal Article

In: Physical Review B, 55 (22), pp. R14733, 1997.

Abstract | Tags: Superconductivity

Pance, K; Zhai, Zhiyong; Srikanth, H; Sridhar, S; Erb, A; Walker, E; Flukiger, R

Microwave response in ultrapure YBa_2Cu_3O_7-x single crystals grown in BaZrO3 crucibles: Effect of oxygen doping Inproceedings

In: APS March Meeting Abstracts, 1997.

Abstract | Tags: Superconductivity

Choudhury, Durga P; Willemsen, Balam A; Derov, John S; Sridhar, S

Nonlinear response of HTSC thin film microwave resonators in an applied DC magnetic field Journal Article

In: IEEE transactions on applied superconductivity, 7 (2), pp. 1260–1263, 1997.

Abstract | Tags: Superconductivity