Large vortex core at low magnetic induction in La2−xSrxCuO4 probed by muon spin rotation

The spatial field distribution in the flux line lattice state of La2−xSrxCuO4 (LSCO) has been studied by muon spin rotation (μSR). In single-crystalline LSCO samples with x=0.13, 0.15, and 0.19, we have observed large vortex cores at low magnetic induction (⩽0.5 T). The possibility of observing a field-induced antiferromagnetic component associated with such large vortex cores is discussed.