Crystal structure and physical properties of half-doped manganite nanocrystals with size < 100nm

Abstract

In this paper we report the structural and property (magnetic and electrical transport) measurements of nanocrystals of half-doped $\mathrm{L}{\mathrm{a}}_{0.5}\mathrm{C}{\mathrm{a}}_{0.5}\mathrm{Mn}{\mathrm{O}}_3$(LCMO) synthesized by chemical route, having particle size down to an average diameter of 15nm. It was observed that the size reduction leads to change in crystal structure and the room temperature structure is arrested so that the structure does not evolve on cooling unlike bulk samples. The structural change mainly affects the orthorhombic distortion of the lattice. By making comparison with observed crystal structure data under hydrostatic pressure it is suggested that the change in the crystal structure of the nanocrystals occurs due to an effective hydrostatic pressure created by the surface pressure on size reduction. This not only changes the structure but also causes the room temperature structure to freeze-in. The size reduction also does not allow the long supercell modulation needed for the Charge Ordering, characteristic of this half-doped manganite, to set-in. The magnetic and transport measurements also show that the Charge Ordering (CO) does not occur when the size is reduced below a critical size. Instead, the nanocrystals show ferromagnetic ordering down to the lowest temperatures along with metallic type conductivity. Our investigation establishes a structural basis for the destabilization of CO state observed in half-doped manganite nanocrystals.

arXiv comment11 pages, 13 Figures

References in corpus (3)

• Novel stripe-type charge ordering in the metallic A-type antiferromagnet Pr{0.5}Sr{0.5}MnO{3}
• Modification of the Charge ordering in Pr${}_{1/2}$Sr${}_{1/2}$MnO${}_3$ Nanoparticles
• Non-linear electrical conduction and broadband noise in charge-ordered rare earth manganate Nd_0.5Ca_0.5MnO_3

Cited by in corpus (9)

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• Magnetocaloric properties of nanocrystalline La${}_{0.125}$Ca${}_{0.875}$MnO${}_3$
• Size control of Charge-Orbital Order in Half-Doped Manganite, La${}_{0.5}$Ca${}_{0.5}$MnO${}_3$
• Electrical transport properties of nanostructured ferromagnetic perovskite oxides La_0.67Ca_0.33MnO_3 and La_0.5Sr_0.5CoO_3 at low temperatures (5 K > T >0.3 K) and high magnetic field
• Tunable site- and orbital-selective Mott transition and quantum confinement effects in La${}_{0.5}$Ca${}_{0.5}$MnO${}_3$ nanoclusters
• Magnetocaloric effect and nature of magnetic transition in nanoscale Pr0.5Ca0.5MnO3
• Evolution of orbital phases with particle size in nanoscale stoichiometric LaMnO3