Exploration of spin state and exchange integral of cobalt ions in stoichiometric ZnCo{sub 2}O{sub 4} spinel oxides
- Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China)
This work reports on spin state and exchange integral of cobalt ions in stoichiometric ZnCo{sub 2}O{sub 4} nanoparticles with varying particle size from about 24 to 105 nm. Cobalt ions in ZnCo{sub 2}O{sub 4} nanoparticles are present as trivalence in mixed spin state. The effective magnetic moment is distributed in the range of 2.1 ∼ 1.31 μ{sub B} at room temperature with coarsening of nanoparticles. Further, it is demonstrated that stoichiometric ZnCo{sub 2}O{sub 4} undergoes a magnetic transition from paramagnetism to antiferromagnetism with decrease of temperature, showing a transition temperature of about 5 K. The standard molar entropy and enthalpy for 24 nm ZnCo{sub 2}O{sub 4} are 170.6 ± 1.7 J K{sup −1} mol{sup −1} and 28.2 ± 0.3 kJ mol{sup −1} at 298.15 K, respectively. Based on the heat capacity data, the exchange integral is determined to be 4.16 × 10{sup −22} J. The results report here are really important for further understanding the magnetic and electronic properties of spinel oxides.
- OSTI ID:
- 22591539
- Journal Information:
- Applied Physics Letters, Vol. 108, Issue 14; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANTIFERROMAGNETISM
COBALT IONS
EXPLORATION
MAGNETIC MOMENTS
NANOPARTICLES
OXIDES
PARAMAGNETISM
PARTICLE SIZE
SPECIFIC HEAT
SPIN
SPINELS
STOICHIOMETRY
TEMPERATURE RANGE 0273-0400 K
TRANSITION TEMPERATURE