Low-temperature specific heat of La1-xSrxMnO3+delta

The specific heat of the perovskite manganite La1-xSrxMnO3+delta was measured in the doping regime x = 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 proportional to T-2, is found in LaMnO3 that is attributable to spin excitations in a layered antiferromagnet. Ferromagnetic samples have the expected specific heat term C proportional to T-3/2 due to ferromagnetic spin waves. The exchange coupling (J), electronic linear term (gamma), Debye temperature (theta(D)), and the local field at the Mn site (H-hyp) are extracted from the specific heat as functions of Sr doping.