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

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 $T_{\mathrm{N}}\approx 3$ 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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Cited by in corpus (1)

• Destruction of long-range magnetic order in an external magnetic field and the associated spin dynamics in Cu2GaBO5 and Cu2AlBO5 ludwigites