  An antiferromagnetic ordering in Pb3TeCo3V2O14 takes place through formation
of short range correlation regime with T* ~ 10.5 K and succession of second
order phase transition at TN1 = 8.9 K and first order phase transition at TN2 =
6.3 K. An external magnetic field rapidly destroys magnetic structure at T <
TN2 and influences the magnetic order at TN2 < T < TN1 resulting in complex
magnetic phase diagram of Pb3TeCo3V2O14 as derived from magnetization and
specific heat measurements. The first principles calculations indicate that in
variance with layered crystal structure the magnetic subsystem of Pb3TeCo3V2O14
is quasi-one-dimensional and highly unusual consisting of weakly coupled
triangular tubes.
