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arXiv · 2005.00914

Structure, magnetic and thermodynamic properties of heterometallic ludwigites: Cu2GaBO5 and Cu2AlBO5

R. M. Eremina·T. P. Gavrilova·E. M. Moshkina·I. F. Gilmutdinov·R. G. Batulin·V. V. Gurzhiy·V. Grinenko·D. S. Inosov
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Abstract

We present an extensive study of the structural, magnetic and thermodynamic properties of high-quality monocrystals of the two heterometallic oxyborates from the ludwigite family: Cu$_2$GaBO$_5$ and Cu$_2$AlBO$_5$ in the temperature range above 2 K. The distinctive feature of the investigated structures is the selective distribution of Cu and Ga/Al cations. The unit cell of Cu$_2$GaBO$_5$ and Cu$_2$AlBO$_5$ contains four nonequivalent crystallographic sites of metal ions. Two sites in the structure from four nonequivalent crystallographic sites of metal ions of Cu$_2$GaBO$_5$ are fully occupied by Cu atoms which form the quasi one-dimensional chains along the a-axis. For Cu$_2$AlBO$_5$ all sites are partially occupied by Al and Cu atoms. The joint analysis of low-temperature data on magnetic susceptibility and magnetic contribution to the specific heat showed that Cu$_2$AlBO$_5$ and Cu$_2$GaBO$_5$ exhibit an antiferromagnetic transition at $T_{\rm N} \approx 3$ and 4 K, respectively. The magnetic contributions to the specific heat for both compounds were obtained after subtracting the phonon contribution. It is shown that the external magnetic field above 2.5 T leads to a broadening of the magnetic phase transition indicating suppression of the long-range antiferromagnetic order.

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R. M. Eremina, T. P. Gavrilova, E. M. Moshkina, I. F. Gilmutdinov, R. G. Batulin, V. V. Gurzhiy, V. Grinenko, D. S. Inosov. 2020-05-02. Structure, magnetic and thermodynamic properties of heterometallic ludwigites: Cu2GaBO5 and Cu2AlBO5. https://doi.org/10.1016/j.jmmm.2020.167262

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