Low-Temperature Specific Heat ofLa1−xSrxMnO3+δ

Abstract

The specific heat of the perovskite manganite ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3+\ensuremath{\delta}}$ was measured in the doping regime $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.0$ to 0.3 where at low temperatures the material changes from a layered antiferromagnetic insulator to a ferromagnetic metal. A term in the specific heat, $C\ensuremath{\propto}{T}^{2}$, is found in ${\mathrm{LaMnO}}_{3}$ that is attributable to spin excitations in a layered antiferromagnet. Ferromagnetic samples have the expected specific heat term $C\ensuremath{\propto}{T}^{3/2}$ due to ferromagnetic spin waves. The exchange coupling ( $J$), electronic linear term ( $\ensuremath{\gamma}$), Debye temperature ( ${\ensuremath{\theta}}_{D}$), and the local field at the Mn site ( ${H}_{\mathrm{hyp}}$) are extracted from the specific heat as functions of Sr doping.