Ferromagnetic Enhancement of CE-Type Spin Ordering in(Pr,Ca)MnO3

Abstract

We present resonant soft X-ray scattering (RSXS) results from small band width manganites (Pr,Ca)MnO3, which show that the CE-type spin ordering (SO) at the phase boundary is stabilized only below the canted antiferromagnetic transition temperature and enhanced by ferromagnetism in the macroscopically insulating state (FM-I). Our results reveal the fragility of the CE-type ordering that underpins the colossal magnetoresistance (CMR) effect in this system, as well as an unexpected cooperative interplay between FM-I and CE-type SO which is in contrast to the competitive interplay between the ferromagnetic metallic (FM-M) state and CE-type ordering.

Interface ferromagnetism in a SrMnO3/LaMnO3superlattice

“…The symmetry of the SL reflection allowed us to probe all Mn valences in the interface layers. In addition to Mn 3+ valence resonances of bulk AFM order measurements [8][9][10][11][12][13][14][15][16] , a peak in the resonant line shape, which has not been observed before, is aligned with the fluorescence yield edge for the Mn 4+ valence. We present a model of the x-ray scattering from the SL interfaces, which includes the temperature dependence of the double-exchange hopping frequency t ij and the change in the configurations of the Mn ions in the FM state.…”

“…More recent measurements showed that magnetic and orbital scattering are similar in amplitude 13 , studied the doping dependence 14 , confirmed the separation in energy of Ref. 13 between the magnetic and orbital scattering resonances, 15 and studied their evolution after photoexcitation 16 . The broader features of the measurements are obtained in calculations of line shapes at the Mn L 3,2 edges with atomic multiplet models of magnetic 17 and orbital 18 scattering, and more recently, with a finitedifference method 19 .…”

“…13, 15 We cannot resolve two peaks at C in the SL line shapes at low T, but this suggests that, with the increase of the FM moment at lower T, a T-dependent magnetic scattering contribution is added ∼ 0.2 eV below the charge scattering resonance. This addition to f i of a temperature dependent (δf i ) mag explains the observed variation in line shape at L = 2.…”

Colossal Magnetoresistance in Mn2+ Oxypnictides NdMnAsO1–xFx

“…Above T SR , the data can be fit to the same equation. The -MR is reversible with field and reaches a value of -95 % at 3 K in a 9 T field which is comparable to perovskite and pyrochlore manganites [1][2][3][4][5][6][7][8][9][10] . This is surprising given the very different electronic and magnetic properties of NdMnAsO 0.95 F 0.05 compared to the perovskite and pyrochlore manganites and suggests a novel CMR mechanism.…”

“…proposed that a dynamic Jahn-Teller effect 7 , the double exchange (DE) mechanism and spatial 2 electronic phase separation 8,9 are all essential for the CMR mechanism. The magnetotransport properties of the pyrochlore manganite Tl 2 Mn 2 O 7 5, 6 appear similar to the doped perovskite;…”