Competing Two-phase Coexistence in Doped Manganites: Direct Observations by in situ Lorentz Electron Microscopy
We examined thin epitaxial films La{sub 5/8-y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} (LPCMO:y=0.275-0.3) in situ by Lorentz transmission electron microscopy (TEM) and other microscopy methods. Clear evidence was obtained for the competing two-phase coexistence of antiferromagnetic charge-ordered (CO) and ferromagnetic (FM) phases that exhibit mesoscale phase separation below the metal-to-insulator transition (MIT) at -164 K. In addition, we observed some regions of mixed CO- and FM-domain contrast attributed earlier to formation of the new CO-FM phase. Using in situ heating/cooling TEM experiments, we interpret this effect as the interfacial wetting phenomenon inherent to the first-order CO-FM phase transition, rather than to the formation of new CO-FM phase. It is evidenced by the partial magnetic melting of CO phase at interfaces with the FM phase, thereby creating charge-disordered spin-glass metastates. For coexisting CO- and FM-domain configurations, we directly refined the relationship between charge-orbital and spin-ordering vectors, consistent with FM moments pinned by (101)-crystal twins in LPCMO films. We also discuss the striking linear dependence observed below MIT for the log-resistance behavior and the CO fraction in LPCMO directly measured by TEM. Such linear dependence does not follow typical percolation equations, suggesting that percolation model needs further revisions for transport description of manganites.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1025428
- Report Number(s):
- BNL-95019-2011-JA; KC0201010; TRN: US1104870
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 82, Issue 22; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
Similar Records
Impact of nanostructuring on the magnetic and magnetocaloric properties of microscale phase-separated La5/8–yPryCa3/8MnO₃ manganites
SISGR: Atom chip microscopy: A novel probe for strongly correlated materials