Charge ordering and magnetoresistance of Ca{sub 1{minus}x}Ce{sub x}MnO{sub 3}

Journal Article · Fri Jun 01 04:00:00 EDT 2001 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.63.224410· OSTI ID:40203487

Zeng, Z; Greenblatt, M; Croft, M

The two-electron (2e) doped Ca{sub 1{minus}x}Ce{sub x}MnO{sub 3} (0{le}x{le}0.2) system was prepared by sol-gel method and investigated by x-ray absorption spectroscopy (XAS), X-ray diffraction, and temperature and field dependent magnetic and transport measurements. The results are compared in detail to the one-electron (1e)-doped La{sub 1{minus}y}Ca{sub y}MnO{sub 3} system, facilitated by the analogous y=1{minus}2x parametrization as Ca{sub (1+y)/2}Ce{sub (1{minus}y)/2}MnO{sub 3} (0.6{le}y{le}1.0). The XAS results indicate: that the formal valence of cerium is Ce{sup 4+}, thereby validating the charge transfer of 2e per doped Ce to Mn. The XAS also shows separate Mn{sup 3+} and Mn{sup 4+} spectral components, in dramatic contrast to results on 1e-doped systems. Low Ce doping (x=0.025 and 0.05) rapidly stabilizes a robust ferromagnetic component in addition to a persistent antiferromagnetic component in the ordered state. Higher Ce doping (0.075{le}x{le}0.20) induces a charge/orbital ordering transition that increases with composition to near 255 K. In different composition ranges the magnetoresistance manifests inter-grain-tunneling and a field coupling of the local charge/orbital order parameter mechanisms. The latter mechanism appears to induce a large magnetoresistance, as high as {minus}72%, in Ca{sub 0.925}Ce{sub 0.075}MnO{sub 3}.

• Sponsoring Organization: (US)
• OSTI ID: 40203487
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 22 Vol. 63; ISSN 0163-1829
• Publisher: The American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION SPECTROSCOPY
CERIUM
MAGNETORESISTANCE
ORDER PARAMETERS
TRANSPORT
VALENCE
X-RAY DIFFRACTION