Thermal and magnetic properties of Cu4O(SeO3)3 composed by ferrimagnetic O2Cu6 units of edge-sharing OCu4 tetrahedra

Monoclinic Cu4O(SeO3)3 has been prepared hydrothermally with subsequent heating in evacuated silica tubes. It has been characterized in measurements of dc and ac magnetic susceptibility chi and specific heat Cp. The title compound orders magnetically at T1 = 13.2 K and evidences a pre-transitional anomaly at T2 = 17.2 K. In the range T1 < T < T2, the application of external magnetic field rapidly suppresses excessive magnetization of this intermediate phase, but the hump in specific heat appears. The magnetic system of the title compound is constituted by the layered network of isolated Cu atoms and O2Cu6 units composed by edge-sharing anion-centered OCu4 tetrahedra. First principles calculations provided values of both ferro-magnetic and antiferromagnetic exchange interactions within O2Cu6 units J1 - J11 and J12 - J22, and anti-ferromagnetic intralayerJ23 - J30 and interlayerJ31 - J32 exchange interactions. Basing on signs and values of these interactions a magnetic model of monoclinic Cu4O(SeO3)3 is suggested.(c) 2023 Published by Elsevier B.V.