Volume 85, Number 6, March 2009
Article Number 67001
Number of page(s) 4
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 26 March 2009
EPL, 85 (2009) 67001
DOI: 10.1209/0295-5075/85/67001

Phonon echo in superconducting MgB2

I. V. Pleshakov1, E. Ylinen2, P. Paturi2, V. V. Matveev3 and R. Laiho2

1   Laboratory for Quantum Electronics, A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences 194021, Saint Petersburg, Russia
2   Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku FI-20014 Turku, Finland, EU
3   Department of Quantum Magnetic Phenomena, St.-Petersburg State University - 198504 Saint Petersburg, Russia

received 21 October 2008; accepted in final form 19 February 2009; published March 2009
published online 26 March 2009

The phonon echo excited by radio-frequency pulses in superconducting MgB2 in external magnetic field was studied. Using the echo technique two contributions to ultrasound attenuation are observed: low-temperature relaxation, which depends on the magnetic field, and a decay connected to the superconducting energy gap at temperatures close to $T_{{\rm c}}$. The value of about $7k_{{\rm B}}T_{{\rm c}}$ for the energy gap was extracted from the experimental data.

74.25.Ld - Mechanical and acoustical properties, elasticity, and ultrasonic attenuation.
74.25.Nf - Response to electromagnetic fields (nuclear magnetic resonance, surface impe- dance, etc.).
74.70.Ad - Metals; alloys and binary compounds (including A15, MgB2, etc.).

© EPLA 2009