Infrared Absorption from Charge Density Waves in Magnetic Manganites
Infrared Absorption from Charge Density Waves in Magnetic Manganites
The infrared absorption of charge density waves coupled to a magnetic background is first observed in two manganites ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ with $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.5$ and $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.67$. In both cases a BCS-like gap $2\ensuremath{\Delta}(T)$, which for $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.5$ follows the hysteretic ferromagnetic-antiferromagnetic transition, fully opens at a finite ${T}_{0}<{T}_{N}$, with $2\ensuremath{\Delta}({T}_{0})/{k}_{B}{T}_{c}\ensuremath{\simeq}5$. These results may also …