Low-Field Magnetization of Ludwigites
Co₃O₂BO₃ and Co_3xFe_xO₂BO₃ (x 0.14)

N. V. Kazak^a*, N. B. Ivanova^b, V. V. Rudenko^a, A. D. Vasil’ev^a,
D. A. Velikanov^a, and S. G. Ovchinnikov^a

^a Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Akademgorodok 50,
Krasnoyarsk, 660036 Russia

*e-mail: nat@iph.krasn.ru

^b Siberian Federal University, pr. Svobodny 79, Krasnoyarsk, 660041 Russia

Received August 28, 2008

Abstract—Ludwigite single crystals of compositions Co₃O₂BO₃ and Co_3xFe_xO₂BO₃ (x 0.14) have been
synthesized. The crystal structure is investigated at room temperature, and the magnetization is studied in the
temperature range T = 4.2–100 K in magnetic fields of up to 600 Oe. The orthorhombic symmetry is revealed,
and the unit cell parameters are determined. A number of features are established for the temperature depen-
dence of the magnetization. In unsubstituted Co₃O₂BO₃, two magnetic transitions are found at T_C1 = 43 K
and T_C2 = 15 K. At temperatures below 40 K, spin-glass state is revealed. Substitution of iron ions for cobalt
ions leads to a noticeable shift in the magnetic transitions toward the high-temperature range: T_C1 = 83 K and
T_C2 = 74 K. A ferromagnetic ordering of the P type is found in the Co_3xFe_xO₂BO₃ (x 0.14) compound.

PACS numbers: 75.30.+h, 72.80.Ga

DOI: 10.1134/S1063783409050138

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