Transformation Of Magnetic Transitions and Crystal Structure of NdBaMn2O6 At Diamagnetic Dilution with Ti4+ Ions in the Mn-Sublattice

Resumo

Magnetic and structural transitions in NdBaMn_2−xTi_xO₆ (x = 0, 0.2) samples obtained by the topotactic procedure at 1373 K and lgPO₂=−19 atm are studied by low-temperature X-ray diffraction and magnetometry in 1–5 T fields. Undoped double manganite undergoes a reversible ferromagnet—antiferromagnet magnetic phase transition at Т_N = 278 K without changing symmetry. The 20 mol.% titanium substitution for manganese causes a decrease in symmetry from the tetragonal space group P4/mmm to the orthorhombic space group Pmmm and a shift of magnetic transitions to lower temperatures. Oxide NdBaMn₂O₆ demonstrates high values of the magnetocaloric effect in the temperature range 250–315 K.