Martensitic accommodation strain and the metal-insulator transition in manganites

Impact of nanostructuring on the magnetic and magnetocaloric properties of microscale phase-separated La5/8−yPryCaBingham1, Lampen2, Phan3 et al. 2012Phys. Rev. B

“…The field-sensitivity and balance of the coexisting phases is affected as the FM component is strengthened and becomes dominant below 100 nm. Our observation that the FM phase is stabilized on the nanoscale is contrasted with the earlier finding 20 that charge disordered PM becomes dominant with grain size reduction on the microscale, demonstrating that in terms of the characteristic phase separation length, a few microns and several hundred nanometers represent very different regimes in microscale phase separated LPCMO. A simple "geometric" model is proposed to illustrate the effects of particle size on the phase coexistence in LPCMO.…”

“…2 (d), only the signature of single-phase FM ordering is evident in the M -T curves of the 55 nm particles. The trend of stabilization of the FM phase on the nanoscale contrasts with what occurs on the microscale (Podzorov et al 20 showed that charge disordered PM became dominant with grain size reduction on the microscale), demonstrating that in terms of the characteristic phase separation length, several hundred nanometers represents a very different regime from the microscale in LPCMO.…”

“…We note that these studies of grain size reduction in polycrystalline LPCMO have not crossed the ~100nm threshold, below which surface effects dominate the physics of manganite nanoparticles. 43 With the exception of our previous study on a closely related composition, 10 we find that despite wealth of available literature on thin films, [29][30][31][32][33][34][35][36][37]41 single- 19,22,25,26,28,40 and polycrystalline 8,9,14,17,18,20,21,23,24,45 forms of LPCMO, virtually no work has been done on nanoparticles of the same compounds, although reduction of particle size to well below the characteristic phase separation length can be expected to have a great impact on strain, and consequently on the magnetic properties of the system. 10 Adding an additional layer of interest, opposing surface-driven trends are observed in nanosized FM and CO compounds.…”

Visualization of a ferromagnetic metallic edge state in manganite strips

“…As shown in Supplementary Figs 8 and 9, pronounced edge phases have been consistently observed in these two systems as well, which strongly indicates that the observed edge phase is not caused by the edge strain effect. This means that the edge phase is clearly different from the strain-induced grain boundary effect observed in manganites bi-crystals 14,15 or polycrystals 16,17 . ARTICLE A plausible mechanism of the edge phases in the manganite strips is the broken symmetry effect of the CE phase.…”

“…These features make manganites the ideal system in which to study edge state physics among complex oxides systems. Although surface [11][12][13] and grain boundary effects [14][15][16][17] have been observed in manganites systems, it is very interesting to verify whether broken symmetry effect can introduce intrinsic edge states in manganites, especially when EPS dominates the system. For this reason, we have chosen a model system of La 0.325 Pr 0.3 Ca 0.375 MnO 3 (LPCMO) which has been well known for its striking large length scale EPS between ferromagnetic metallic (FM) and CE-type antiferromagnetic charge-ordered insulating (CE) phases 18 .…”