Successive phase transitions in a metal-ordered manganite perovskite YBaMn2O6

Abstract

Structural, magnetic and electric properties of a metal-ordered perovskite YBaMn 2 O 6 have been studied by means of powder X-ray diffraction, DSC, magnetic susceptibility, and electric resistivity. It is found that this material undergoes a 1st order structural phase transition at T c1 =520 K, from a pseudo orthorhombic (monoclinic) phase (T c1 <T) to a pseudo tetragonal (monoclinic) one (T<T c1 ). Accompanied by this transition, the susceptibility exhibits a sharp drop, where ferromagnetic exchange interaction becomes antiferromagnetic. Furthermore, two more transitions, a metal-insulator transition at T c2 =480 K and an antiferromagnetic ordering at T c3 =200 K, have been observed respectively.

Oxygen and cation ordered perovskite, Ba2Y2Mn4O11

“…Iodometric titration revealed a value of 0.97 (1) for the amount of excess oxygen, δ, in the O 2 -annealed sample. We may thus conclude in agreement with previous reports [17,20] that an essentially fully-oxygenated BaYMn 2 O 5+δ (with δ ≈ 1) phase has been obtained from the oxygen-depleted BaYMn 2 O 5+δ (with δ ≈ 0) sample by means of the low-temperature O 2 annealing.…”

“…The synchrotron x-ray diffraction data confirmed that the present oxygen-getter-controlled low-O 2 -pressure encapsulation synthesis had yielded high-quality double-perovskite samples of [17,18], were detected. We expect that the oxygen partial pressure at the synthesis temperature, i.e.…”

“…This is in drastic contrast to the case of the BaRECo 2 O 5+δ double perovskites [13] for which continuous tuning of oxygen nonstoichiometry within 0 < δ < 0.7 is possible by selecting a proper temperature for the N 2 annealing in the temperature range of 300 -1000 o C, i.e. Among these, the first [9,20] and the last [17,22] are close to those reported in Ref. [22].…”

Oxygen and cation ordered perovskite, Ba2Y2Mn4O11

“…Once the A-site ordered, oxygen-deficient (here δ ≈ 0) double-perovskite framework of Among these, the first [9,20] and the last [17,22] are close to those reported in Ref. [22].…”

Theoretical study of half-doped models for manganites: Fragility of CE phase with disorder, two types of colossal magnetoresistance, and charge-ordered states for electron-doped materials

“…The present results are in excellent agreement with the recent experimental studies of Ln 1/2 La 1/2 MnO 3 (Ln = rareearth) by Akahoshi et al 11 and Nakajima et al 12 . In these experiments it was observed that the phase diagram has bicritical behavior (Fig.…”