High pressure floating zone growth and structural properties of ferrimagnetic quantum paraelectric BaFe 12 O 19
High quality single crystals of BaFe$$_{12}$$O$$_{19}$$ were grown with the floating zone technique in flowing oxygen atmosphere of 100 atm. BaFe$$_{12}$$O$$_{19}$$ melts incongruently in atmospheric oxygen. High oxygen pressure above 50 atm modifies the melting behavior to be congruent, which allows for the crystal growth with the crucible-free floating zone technique. Single crystal neutron diffraction were measured to determine the nuclear and magnetic structures at 4 K and 295 K. At both temperatures, there exist local electric dipoles formed by the off-mirror-plane displacements of magnetic Fe$$^{3+}$$ ions at the bypyramidal sites. The displacement at 4 K is about half of that at room temperature. The temperature dependence of specific heat shows no anomaly associated with the long range polar ordering in the temperature range of 1.90-300~K. The inverse dielectric constant along the c-axis shows a $T^2$ temperature dependence below 20 K and then following by a plateau below 10 K, recognized as quantum paraelectric features. Further cooling below 1.4 K, the upturn region was clearly revealed and indicates BaFe$$_{12}$$O$$_{19}$$ is a critical quantum paraelectric system with Fe$$^{3+}$$ ions playing roles for both magnetic and electric dipoles.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1188512
- Alternate ID(s):
- OSTI ID: 1215578; OSTI ID: 1421236
- Journal Information:
- APL Materials, Journal Name: APL Materials Vol. 3 Journal Issue: 6; ISSN 2166-532X
- Publisher:
- American Institute of PhysicsCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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