Unusual temperature dependence of the oxygen-isotope effect on the exchange-energy of $L{a}_{1-x}C{a}_{x}Mn{O}_3$ at high temperatures

Abstract

We report magnetic susceptibility $\chi (T)$ measurements on oxygen-isotope exchanged La${}_{1-x}$Ca${}_x$MnO${}_{3+y}$ up to 700 K. The $1/\chi (T)$ data show that the ferromagnetic exchange-energy $J$ depends strongly on the oxygen-isotope mass. The isotope effect on $J$ decreases with temperature up to 400 K and then increases again with temperature above 400 K. This unusual temperature dependence of the isotope effect cannot be explained by existing theories of the colossal magnetoresistance effect for doped manganites. The present results thus provide essential constraints on the physics of manganites.

4 pages, 5 figures

References in corpus (4)

• Carrier Density Collapse and Colossal Magnetoresistance in Doped Manganites
• Electrical transport in the ferromagnetic state of manganites: Small-polaron metallic conduction at low temperatures
• Evidence for the immobile bipolaron formation in the paramagnetic state of the magnetoresistive manganites
• Double-exchange is not the cause of ferromagnetism in doped manganites

Cited by in corpus (1)

• Correlation Between Phase Competition and the Nucleation of a Griffiths Phase in (La1-yPry)0.7Ca0.3Mn16/18O3