Zero-field resistivity anomaly and low-field response of the canted antiferromagnetism in unsubstituted and Ba-substituted LaMnO{sub 3+{delta}} within the insulating regime
Journal Article
·
· Physical Review, B: Condensed Matter
- Electroceramics Laboratory, Central Glass Ceramic Research Institute, Calcutta 700 032 (India)
Electrical and low-field magnetic properties of unsubstituted LaMnO{sub 3+{delta}} and Ba-substituted La{sub 1{minus}y}Ba{sub y}MnO{sub 3+{delta}} systems have been measured over the temperature range 20{endash}300 K. The samples within the insulating regime exhibit {rho}={rho}{sub 0}thinspexp(U/k{sub B}T) type resistivity ({rho}) vs temperature (T) pattern (U=activation barrier). However, for the unsubstituted samples with {delta}=0.031{endash}0.064 and Ba-substituted ones up to a doping level of y=0.05, an anomalous deviation in the {rho} vs T pattern has been observed below the antiferromagnetic ordering temperature (T{sub A}) which yields a significantly smaller activation barrier in this low-temperature regime. Such an anomaly in {rho} vs T arises in this temperature regime (where A-type antiferromagnetic spin structure is dominant) possibly due to confinement of charge carriers within the two-dimensional Mn-O planes in a grain. In the case of Ba-substituted samples, the insulator-to-metal transition takes place at a relatively higher doping level (y{ge}0.2) than what is normally observed in the case of Sr or Ca doping. The insulating samples also exhibit a significant drop in T{sub A} under a low magnetic field (100{endash}5000 Oe). This observation reveals a canted A-type antiferromagnetic structure (rather than a spiral structure) for these samples, as pointed out recently by Kawano {ital et al.} [Phys. Rev. B {bold 53}, 2202 (1996)]. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 632632
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 14 Vol. 56; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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