ISSN:
1572-9605
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Physics
Notes:
Abstract Oxygen isotope effect studies of the ferromagnetic Curie temperature T c of La1−x Ca x MnO3 are presented. The isotope exponent α0=−ΔlnT c/Δlnm 0 changes from 0.4 to 0.14 in the range 0.2〈x〈0.43. The isotope exponent decreases strongly with increasing tolerance factor, or decreasing lattice distortion. Above Tc the conductivity is characteristic of small polarons. Raman scattering shows a prominent peak at 230 cm−1. The peak width could be related to site-dependent Jahn–Teller distortions above T c, becoming significantly smaller at and below T c. IR reflectivity data show a much larger zero frequency IR conductivity than dc conductivity. The IR peaks are independent of temperature between 150 and 295 K.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007764223904
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