ON THE EFFECT OF LOW-TEMPERATURE DEMAGNETIZATION ON TRMS AND PTRMS

Low-temperature demagnetization (LTD) experiments with TRMs and pTRMs using liquid nitrogen were carried out on samples with different (MD a nd PSD) domain structures to infer and to compare the type of domain s tructure of samples before and after LTD judged by the thermomagnetic criterion. This is based on testing materials against Thellier's law o f independence of pTRMs. The results demonstrate good agreement betwee n the commonly used criteria for differentiating domain structure, suc h as Q(rt), H-cr/H-c and I-rs/I-s factors, and more sophisticated ones , such as the thermomagnetic criterion and LTD treatment. It is notewo rthy that there is no observable tendency of MD or PSD samples to disp lay SD-type pTRM =f(T) curves after LTD treatment. Hence our experimen ts failed to detect a quasi-SD component of remanence acquiring TRM by thermofluctuations in MD or PSD grains in the manner of Verhoogen (19 59) and Stacey & Banerjee (1974) hypotheses