Direct evidence of phase segregation and magnetic-field-induced structural transition inNd0.5Sr0.5MnO3by neutron diffraction

We present direct evidence of the phase segregation and magnetic-field-induced structural transition in ${\mathrm{Nd}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3}$ as proposed earlier [R. Mahendiran et al., Phys. Rev. Lett. 82, 2191 (1999)] for the collapse of the charge-ordered insulating state. The spontaneous $(H=0)$ low-temperature phase at 125 K is found to be phase segregated into two different crystallographic structures and three magnetic phases: orthorhombic (Imma) ferromagnetic, orthorhombic (Imma) A-type antiferromagnetic, and monoclinic ${(P2}_{1}/m)$ charge-ordered CE-type antiferromagnetic phases. Under a field of $H=6$ T, the charge-ordered monoclinic phase collapses and completely transforms into the metallic ferromagnetic orthorhombic phase.