Magnetic Phase Separation in Double Perovskite Sr 2 TiMnO 5.87

The double perovskite Sr 2 TiMnO 5.87 was synthesized via the solution combustion precursor method using Sr(NO 3 ) 2 , MnO 2 , i-Ti(OC 3 H 7 ) 4 , and disubstituted ammonium citrate as a complexing agent. The crystal structure and unit cell parameters are refined by the Rietveld method using powder X-ray diffraction. The magnetic properties of double perovskites Sr 2 TiMnO 5.87 were studied using the ESR spectroscopy, specific heat measurements in the temperature range ~ 5–300 K, and magnetometry under cooling in zero- (ZFC) and nonzero-fields (FC). The four ESR line were observed in ESR spectra, three ESR lines with g ~ 2 and fourth ESR at B res = 50 mT in both X-and Q-bands measurements in the temperature range 37.5–42 K in Sr 2 TiMnO 5.87 . The peaks obtained in real and imaginary parts of AC magnetization measurements confirm phase separation at the same temperatures. The antiferromagnetic ordering was found out below the temperature T N ≈ 12 K. The fitting Debye and Einstein temperatures, obtained from the specific heat measurements, are equal to θ D = 217 K, θ E1 = 275 K, θ E2 = 615 K, and θ E3 = 2000 K.