Fabrication and femtosecond photoresponse studies of MgB2 superconducting thin films

Ying Xu; Marat Khafizov; Andrej Plecenik; Peter Kus; Leonid Satrapinsky; Roman Sobolewski

doi:10.1117/12.455833

7 November 2002 Fabrication and femtosecond photoresponse studies of MgB₂ superconducting thin films

Ying Xu, Marat Khafizov, Andrej Plecenik, Peter Kus, Leonid Satrapinsky, Roman Sobolewski

Proceedings Volume 4811, Superconducting and Related Oxides: Physics and Nanoengineering V; (2002) https://doi.org/10.1117/12.455833
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

Abstract

We present fabrication and optical time-resolved photoresponse characterization of MgB₂ superconducting thin films. The films were prepared on crystalline and flexible plastic substrates by vacuum co-deposition of B and Mg precursors and high-temperature annealing in an Ar or vacuum atmosphere. The post-annealed films exhibited very smooth surfaces and amorphous structures with nanocrystal inclusions. The best films exhibited the critical temperature Tc of up to 38 K, the transition width of 1 K, and the current density j_c at 4.2 K of about 10⁶ A/cm². In our pump-probe photoresponse experiments, we used 100-fs-wide optical pulses generated by a Ti:Sapphire laser. The pump and the probe beams had 800-nm wavelength and the measurements were performed in the temperature range from 3.5 K to room temperature. The transient reflectivity change (ΔR/R) signals exhibited around 300-fs (10%-90%) risetime. At room temperature and far above Tc, (ΔR/R) the transient reflectivity change was characterized by a ~160-fs, single-exponential decay, interpreted as the electron-Debye-phonon interaction time. Below 60 K and in the superconducting state, the ΔR/R photoresponse was biexponential, with the initial femtosecond decay followed by a much slower, several-ps-long relaxation. We associate the latter slow relaxation with the electron-phonon interaction related to the Cooper pair recombination dynamics. The existence of this signal above the nominal T_c of our films, we tentatively interpret as the presence of superconducting fluctuations in our MgB₂ films. Our work gives the first insight into the carrier dynamics in MgB₂ by time-resolved experimental studies of the Cooper pair breaking and thermalization mechanisms for the films perturbed by femtosecond optical excitations.

Citation Download Citation

Ying Xu, Marat Khafizov, Andrej Plecenik, Peter Kus, Leonid Satrapinsky, and Roman Sobolewski "Fabrication and femtosecond photoresponse studies of MgB₂ superconducting thin films", Proc. SPIE 4811, Superconducting and Related Oxides: Physics and Nanoengineering V, (7 November 2002); https://doi.org/10.1117/12.455833

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
11 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Superconductors

Thin films

Femtosecond phenomena

Temperature metrology

Phonons

Crystals

Magnesium

Show All Keywords

Keywords/Phrases

Search In:

Publication Years