Variations in elastic and anelastic properties of Co3O4 due to magnetic and spin-state transitions

Autor(en)

Zhiying Zhang, Johannes Koppensteiner, Wilfried Schranz, Michael Allan Carpenter

Abstrakt

Elastic anomalies and acoustic dissipation associated with spin-state transitions of Co3+ in Co3O4 have been investigated using resonant ultrasound spectroscopy (RUS) at high frequencies (0.1-1.5 MHz) between 6 and 1107 K, and dynamic mechanical analysis (DMA) at low frequencies (0.1-50 Hz) between 127 and 775 K. Above similar to 800 K, the shear modulus decreases with increasing temperature and the acoustic dissipation increases. The amount of softening scales linearly with an empirical order parameter for low spin -> low spin + high spin states derived from analysis of changes in unit-cell volume with temperature. The mechanism for anelastic losses is not understood but must be due to relaxation of strains coupled either to changes in spin state or to changes of cation configuration between tetrahedral and octahedral sites occurring by electron exchange. The pattern of shear modulus softening, in proportion to the spin order parameter, is likely to be general for cubic structures containing cations, which undergo spin-state transitions, such as Fe2+ in (Mg,Fe)O. Below similar to 30 K, RUS data show a large softening of the shear modulus and a steep increase in acoustic dissipation due to the magnetic transition from paramagnetic to antiferromagnetic. This could be understood in terms of the influence of a symmetry breaking strain coupled to the magnetic order parameter such that cubic lattice geometry is not maintained. Possible magnetic space groups for the antiferromagnetic structure are considered through the use of the group theory.

Organisation(en)

Physik Funktioneller Materialien

Externe Organisation(en)

University of Cambridge

Journal

American Mineralogist: an international journal of earth and planetary materials

Band

97

Seiten

399-406

Anzahl der Seiten

8

ISSN

0003-004X

DOI

https://doi.org/10.2138/am.2012.3901

Publikationsdatum

2012

Peer-reviewed

Ja

ÖFOS 2012

103009 Festkörperphysik, 103008 Experimentalphysik, 103029 Statistische Physik, 103002 Akustik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/abba9165-dd06-47e7-a942-376995e079e3