Spin glass transition of single-crystalline TmFe2O4- δ.
J Phys Condens Matter
; 32(40): 405801, 2020 May 22.
Article
in En
| MEDLINE
| ID: mdl-32442996
ABSTRACT
TmFe2O4 is one kind of multiferroic material in which equivalent amounts of Fe2+ and Fe3+ occupy a two-dimensional triangular lattice, leading to charge and spin frustrations. The spin frustration is expected to be increased as the fraction of Fe2+ (Fe3+) becomes larger than that of Fe3+ (Fe2+). We have grown single-crystalline TmFe2O4-δ with oxygen vacancies by using floating zone melting method and examined its magnetic properties. On cooling the compound, a long-range magnetic ordering develops around â¼240 K. With further cooling, a maximum of zero-field-cooled (ZFC) magnetization is observed at 186.2 K. The ac magnetic susceptibility obtained by ZFC process also manifests a maximum in its temperature dependence, and the variation of spin-freezing temperature with frequency of ac magnetic field is explainable in terms of the dynamic scaling law with the critical component of 8.68(8). This value suggests that the spin glass transition occurs at 186.2 K. The effect of external dc magnetic field on the irreversible transition temperature is coincident with the de Almeida-Thouless (AT) line. Aging-memory and rejuvenation effect is also observed below the spin-freezing temperature. These facts support the idea that TmFe2O4-δ undergoes spin glass transition below the ferrimagnetic transition temperature. In other words, TmFe2O4-δ can be regarded as a reentrance spin glass. It is thought that the oxygen vacancies bring about unequal number of Fe2+ and Fe3+ ions and thereby strengthen the magnetic frustration among the iron ions coupled with antiferromagnetic interactions, leading to the spin glass behavior.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Phys Condens Matter
Journal subject:
BIOFISICA
Year:
2020
Document type:
Article
Affiliation country:
Japan