Magnetic phase diagram and first-principles study of Pb3TeCo3V2O14

An antiferromagnetic ordering in Pb3TeCo3V2O14 takes place through formation of a short-range correlation regime with T* similar to 10.5 K and the succession of a second-order phase transition at T-N1 = 8.9 K and a first-order phase transition at T-N2 = 6.3 K. An external magnetic field rapidly destroys magnetic structure atT < T-N2 and influences themagnetic order at T-N2 < T < T-N1, resulting in a complex magnetic phase diagram of Pb3TeCo3V2O14 as derived from magnetization and specific heat measurements. The first-principles calculations indicate that, in variance with a layered crystal structure, the magnetic subsystem of Pb3TeCo3V2O14 is quasi-one-dimensional and highly unusual, consisting of weakly coupled triangular tubes.