Irradiation-Induced Electron Tunnelling and Small-Polaron Hopping in Single-Crystalline YIG
✍ Scribed by F. Walz; J.H.V.J. Brabers; L. Torres; H. Kronmüller
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 245 KB
- Volume
- 228
- Category
- Article
- ISSN
- 0370-1972
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✦ Synopsis
In electron (e À )-irradiated (>10 23 e À m À2 ) single crystalline yttrium-ion Garnet (YIG), after moderate annealing, low-temperature (T < 125 K) magnetic after-effect (MAE) spectra are observed which are of striking similarity to the well investigated spectra occurring in magnetite (Fe 3 O 4 ) below the Verwey transition (T V % 125 K). Our analysis shows that this similarity is the result of corresponding relaxation mechanisms in both systems, i.e. electron tunnelling and small-polaron hopping. Deeper insights into these mechanisms are obtained from a thorough inspection of these spectra and their physical preconditions in the two, a-priori, completely different ferrimagnetic systems: (i) semiconductor, transformed into a quasi-insulating state due to long-range ionic ordering at low-temperatures (Fe 3 O 4 ) and (ii) insulator, brought into a state of low resistivity due to radiation-induced perturbations of the charge equilibrium (YIG).
In Elektronen (e À )-bestrahltem (>10 23 e À m À2 ) einkristallinem Eisen-Granat (YIG) wird, nach ma ¨ßiger Erholung, bei tiefen Temperaturen (T < 125 K) ein magnetisches Nachwirkungsspektrum beobachtet, das dem gut untersuchten Spektrum in Magnetit (Fe 3 O 4 ), unterhalb des Verwey-Ûbergangs (T V % 125 K) verblu ¨ffend a ¨hnelt. Unsere Untersuchung zeigt, daß diese Øhnlichkeit auf u ¨bereinstimmenden Nachwirkungsmechanismen in beiden Systemen beruht, na ¨mlich Elektron-Tunneln und Klein-Polaron-Hu ¨pfen. Neue Einsichten hinsichtlich dieser Mechanismen erbringt ein sorgfa