Biomedical subjects

P Nalbach

Publications and source records attributed to P Nalbach.

2 recordsLinked to original sources

PubMed2003

Memory effects in amorphous solids below 20 mK.

At temperatures below 1 K, the capacitance of a glass sample changes due to the application of a dc field in accordance with Burin's dipole gap theory [J. Low Temp. Phys. 100, 309 (1995)]]. However, we now report that below 20 mK, during the first sweep cycle of the dc electric field, the capacitance is smaller by about 10(-5) compared to any subsequent sweep. Despite this overall shift, the field dependence follows the dipole gap predictions. In a subsequent sweep to higher dc fields the dielectric constant drops by about 10(-5) as soon as the applied field is higher than any field previously applied. A picture involving the dynamics of resonant pairs provides a qualitative description of this behavior.

Journal Article↗

PubMed2003

Dynamics of the destruction and rebuilding of a dipole gap in glasses.

After a strong electric bias field is applied to the polyester glass Mylar at temperatures in the mK range, its dielectric constant increases and then decays logarithmically in time. We observed its dielectric response for several temperatures and different field sweeps. Starting from the dipole gap theory, we developed a model suggesting that the change in dielectric constant after transient application of a bias field is only partly due to relaxational processes. In particular, nonadiabatic driving of tunneling states (TSs) by applied electric fields causes additional dielectric response. Also, we find that for T less, similar 50 mK the relaxation of TSs is caused primarily by mutual interactions.

Journal Article↗