| Title |
Magnetoresistance and electrical resistance relaxation in La-Sr(Ca)-Mn-O nanostructured films / |
| Translation of Title |
Nanostruktūrizuotų La-Sr(Ca)-Mn-O sluoksnių magnetovarža ir elektrinės varžos relaksacija. |
| Authors |
Pavilonis, Dainius |
| Full Text |
|
| Pages |
113 |
| Keywords [eng] |
magnetoresistance ; manganite ; relaxation ; ageing |
| Abstract [eng] |
The goal of this thesis was to investigate, how chemical composition and morphology of La-Sr(Ca)-Mn-O nanostructured films influences the resistivity and magnetoresistance values in wide range of temperatures and magnetic fields, and to clear up origin of memory effects occurring after the magnetic field pulse affected the films is switched off. It was demonstrated that the magnetoresistance of nanostructured manganite films can be analyzed using modified Mott’s hopping model taking into account contributions of both crystallites and grain boundaries. It was found that resistance relaxation process in these films after magnetic field is switched off has two different components: ‘fast’ (> 100 µs), and ‘slow’ (≥ 1 ms). The characteristic time constants and relative parts of the remnant resistivity of these processes were systematically analyzed in a wide range of temperatures and magnetic fields using Kolmogorov-Avrami-Fatuzo and Kohlrausch–Williams–Watts models. The obtained results enabled to suggest the development of fast high pulsed magnetic field sensors operating at two ranges of temperatures: close to room and cryogenic. It was also shown that the treatment of nanostructured manganite films by annealing them in an argon atmosphere at 100-200 C temperatures accelerates their ageing processes and stabilizes their resistance and magnetoresistance. |
| Dissertation Institution |
Valstybinis mokslinių tyrimų institutas Fizinių ir technologijos mokslų centras. |
| Type |
Doctoral thesis |
| Language |
English |
| Publication date |
2017 |
