ANOMALOUS MODULUS DEFECT DUE TO DISLOCATION PINNING

Abstract
The frequency dependence (10 - 100 MHz) of the dislocation modulus defect (MD) and damping Q^-1 has been measured at RT during γ-irradiation. In very high purity single crystals (resistivity ratio RRR ≈ 10.000) dislocation pinning at low doses leads to an increase of MD at high frequencies. Depinning effects can be excluded because MD at low frequencies and the simultaneously measured Q^-1 at all frequencies show normal dislocation pinning behaviour for all γ-doses. The presently reported anomalous MD-behaviour is predicted by the theory and thus a strong proof for the dislocation resonance mechanism.