High-field Study of Layered Manganites R1/2Sr3/2MnO4 (R = La and Nd)

Abstract

We have studied the effects of a magnetic field on the magnetism and transport properties of the layered manganites R1/2Sr3/2MnO4 (R = La and Nd) in pulsed magnetic fields up to 40 T. The R = La crystal shows metamagnetic-like transitions above 30 T, concomitantly with a colossal magnetoresistance (CMR) effect as large as [ρ(0) - ρ(H)]/ρ(H) > 103 with a field of µοH = 38 T at low temperatures. These transitions can be ascribed to the field-induced melting of the real-space ordering of the eg electrons (charge ordering). For the R = Nd crystal, a magnetic field along the c-axis enhances the two-dimensionality in the conductivity. Moreover, we observed metamagnetic-like transitions accompanied by the CMR effects at low temperatures, in spite of the absence of charge ordering.

Charge ordering in the rare earth manganates: the experimental situation

“…The order parameter for charge ordering appears to evolve along with that due to orbital ordering. Application of high magnetic fields causes metamagnetic transitions below T co ; both charge and orbital orderings are destroyed by the magnetic field [52]. Thermal conductivity measurements show the prevalence of stripe correlations [53], just as in Ln 1.67 Sr 0.3 NiO 4 .…”