Microwave tunnel echo in glass
Smolyakov B.P., Khaimovich E.P.
A microwave echo was observed for the first time in glass without magnetic impurities. A dependence of the echo signal on the magnetic field was obtained in glass with rare-earth impurities. It was found that the relaxation times decrease as a result of application of the field. It is assumed that the observed signals are due to the spectrum of low-frequency excitations caused by tunneling.