Effect of R substitution in spin glass RFeTi2O7 compounds | Научно-инновационный портал СФУ

Effect of R substitution in spin glass RFeTi2O7 compounds

Тип публикации: статья из журнала

Год издания: 2020

Идентификатор DOI: 10.1016/j.jmmm.2020.167273

Ключевые слова: anisotropic exchange, anisotropy, frustration, magnetism, spin glass

Аннотация: Zirconolite oxides R3+Fe3+Ti2O7 (R rare earth element) are known to exhibit spin glass behaviour at low temperatures. Here we present a detailed study of these compounds for R = Eu, Gd, Dy, Ho, and Er, together with reviewed previous measurements on Sm, Tb, Tm, Yb and Lu, with the scope of determining the role played by the rare earth on their magnetic properties. They have been investigated using X-ray powder diffraction, and further characterized by magnetization, frequency dependent ac susceptibility and heat capacity measurements. RFeTi2O7 compounds are all isostructural showing orthorhombic structure, space group Pcnb at 300 K. Disorder of the magnetic ions in the RFeTi2O7 lattice induces spin glass behaviour at low temperatures, mainly due to the Fe sublattice. We show that magnetic rare earth ions participate in the spin glass state tuning its properties. The single ion anisotropy of the R3+ ions, excluding exchange interaction with other magnetic ions, has been calculated by ab initio methods, and expressed in terms of the g tensor of the ground doublet or quasi-doublet in Kramers (Sm, Dy, Er, Yb) and non-Kramers (Tb, Ho) ions, respectively, in an effective spin S* = 1/2 model. In the case of R with a singlet ground state (Eu, Tm) or a multiplet state (Gd), the ion is isotropic. We show that the relative increase in the spin-glass temperature ΔTSGR/TSGFe with respect to the LuFeTi2O7, where Lu is non-magnetic, correlates qualitatively with the product of the ratio gz/gJ (R = Tb, Dy, Ho, and Er), or g⊥/gJ (R = Sm), times the ratio of exchange interactions [Formula presented] determined from the paramagnetic room temperature susceptibility measurements. Besides, for increasing anisotropy the spin glass transition dynamics slows down to values typical of cluster glass. The coercive field below the transition is increased in the same trend. This paper explains the effect of the R-Fe exchange interaction and R single ion anisotropy on the spin-glass behaviour of these compounds. © 2020 Elsevier B.V.

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Издание

Журнал: Journal of Magnetism and Magnetic Materials

Выпуск журнала: Vol. 515

Номера страниц: 167273

ISSN журнала: 03048853

Авторы

  • Arauzo A. (Univ Zaragoza, Inst Nanociencia & Mat Aragon INMA, CSIC, Zaragoza 50009, Spain; Univ Zaragoza, Dept Fis Mat Condensada, CSIC, Zaragoza 50009, Spain; Univ Zaragoza, Serv Medidas Fis, E-50009 Zaragoza, Spain)
  • Bartolome J. (Univ Zaragoza, Inst Nanociencia & Mat Aragon INMA, CSIC, Zaragoza 50009, Spain; Univ Zaragoza, Dept Fis Mat Condensada, CSIC, Zaragoza 50009, Spain)
  • Luzon J. (Acad Gen Mil, Ctr Univ Def, Zaragoza, Spain)
  • Drokina T. (Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Akademgorodok 50-38, Krasnoyarsk 660036, Russia)
  • Petrakovskii G.A. (Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Akademgorodok 50-38, Krasnoyarsk 660036, Russia)
  • Molokeev M.S. (Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Akademgorodok 50-38, Krasnoyarsk 660036, Russia; Siberian Fed Univ, Krasnoyarsk 660041, Russia)

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