Thermodynamic Measurements of Magnetic Ordering in Antiferromagnetic Superlattices

Journal Article · Tue Oct 01 04:00:00 EDT 1996 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.77.3451· OSTI ID:388400

Abarra, E N; Takano, K; Hellman, F; Berkowitz, A E ^[1]

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1. Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)

Direct measurements of heat capacity from 80 to 540K of antiferromagnetic superlattices of NiO (high N{acute e}el temperature {ital T}{sub {ital N}}), CoO (low {ital T}{sub {ital N}}), and MgO (nonmagnetic) are used to study the effect of exchange coupling and layer thickness on magnetic ordering. NiO/CoO superlattices with thin layers show a single heat capacity peak similar to a Ni{sub 0.5}Co{sub 0.5}O alloy; with increasing layer thickness, the peak splits into two maxima. Finite size effects are seen in uncoupled NiO and CoO. Observed shifts in {ital T}{sub {ital N}} show the importance of correlation lengths and spin fluctuations in the ordering. {copyright} {ital 1996 The American Physical Society.}

• DOE Contract Number: FG03-95ER45529
• OSTI ID: 388400
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 16 Vol. 77; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIFERROMAGNETIC MATERIALS
COBALT OXIDES
CORRELATION FUNCTIONS
EXCHANGE INTERACTIONS
MAGNETIC SPECIFIC HEAT
NICKEL OXIDES
SPECIFIC HEAT
SUPERLATTICES
TEMPERATURE DEPENDENCE
X-RAY DIFFRACTION