Volume 34, Number 5, May II 1996
|Page(s)||379 - 384|
|Section||Condensed matter: electronic structure, electrical, magnetic and optical properties|
|Published online||01 September 2002|
Chemical tuning of the colossal magnetoresistance of ferromagnetic perovskites
Institut de Ciència de Materials de Barcelona CSIC,
Campus Universitat Autònoma de Barcelona - Bellaterra 08193, Catalunya, Spain
Accepted: 21 March 1996
The colossal magnetoresistance (CMR) of a series of ferromagnetic perovskites is explored for a wide range of lanthanides (L) having different ionic radii. It is shown that the CMR can be tuned through the appropriate size of the lanthanide. The negative magnetoresistance has been modified in this way by two orders of magnitude, reaching values higher than %. We will show that the temperature (TM) where magnetoresistance is maximum correlates with its intensity () and we will argue that both effects are simply controlled by the bending of the Mn—O—Mn bond. Above TM, the enhancement of resistivity when decreasing the temperature can be described by a Variable Hopping model in which the relevant localization length l is found to be reduced when increasing the lattice distortion; inversely l enhances when applying a magnetic field, thus explaining the observation of a negative magnetoresistance. The giant modification of the electrical resistance goes in parallel with an unusually high magnetic polarizability. We argue that the coupling of itinerant charge carriers (holes) and their reduced mobility when they polarize the localized moments, thus forming magnetic polarons, lie at the heart of the CMR.
PACS: 71.30.+h – Metal-insulator transitions / 71.28.+d – Narrow-band systems; heavy-fermion solids; intermediate-valence solids / 72.20.My – Galvanomagnetic and other magnetotransport effects
© EDP Sciences, 1996
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.