Magnetic properties of Nd-deficient manganites Nd0.9−Ca MnO

Metastable diamagnetic response of20nmLa1−xMnO3particles

“…[1][2][3][4][5][6][7][8] Different scenarios were proposed to tackle this abnormal behavior: ͑i͒ a structural phase transition leading to a reversal of the Dzyaloshinskii vector; 1,2 ͑ii͒ a negative coupling between sublattices of 3d and 4f ions, leading to a sort of ferrimagnetism; 3-7 ͑iii͒ a change of sign in the d-f exchange interactions. 8 It is well known that DzyaloshinskiiMoriya antisymmetric exchange 9,10 is responsible for slight canting of the spins of antiferromagnetic ͑AFM͒ sublattices, resulting in a weak ferromagnetic ͑FM͒ component ͑Dzyaloshinskii vector͒. Usually, this weak FM moment is equal to 10 −2 -10 −5 of the maximal magnetization of the nominal magnetic moments.…”

“…Usually, this weak FM moment is equal to 10 −2 -10 −5 of the maximal magnetization of the nominal magnetic moments. Since "anomalous diamagnetism" in perovskite orthovanadates was attributed to reversal of the Dzyaloshinskii vector, 1,2 the negative magnetization observed in these compounds was relatively small, less than 10 −2 emu/ g. 1,2 Negative magnetization was observed also in some manganites, such as ͑Dy, Ca͒MnO 3 , 3,4 Gd 0.67 Ca 0.33 MnO 3 , 5 La 1−x Gd x MnO 3 , 6 NdMnO 3+␦ , 7 Nd 1−x Ca x MnO y , 8 and ͑Nd, Ca͒͑Mn, Cr͒O 3 . 8 The reversal of magnetization in these compounds was attributed to a ferrimagneticlike behavior due to the interplay of two antiferromagnetically coupled magnetic sublattices: the rare-earth sublattice and the Mn sublattice.…”

“…Since "anomalous diamagnetism" in perovskite orthovanadates was attributed to reversal of the Dzyaloshinskii vector, 1,2 the negative magnetization observed in these compounds was relatively small, less than 10 −2 emu/ g. 1,2 Negative magnetization was observed also in some manganites, such as ͑Dy, Ca͒MnO 3 , 3,4 Gd 0.67 Ca 0.33 MnO 3 , 5 La 1−x Gd x MnO 3 , 6 NdMnO 3+␦ , 7 Nd 1−x Ca x MnO y , 8 and ͑Nd, Ca͒͑Mn, Cr͒O 3 . 8 The reversal of magnetization in these compounds was attributed to a ferrimagneticlike behavior due to the interplay of two antiferromagnetically coupled magnetic sublattices: the rare-earth sublattice and the Mn sublattice. If the magnetizations of the two sublattices have different temperature dependences and, at decreasing temperature, the magnetization of the sublattice aligned antiparallel with the magnetic field ͑rare-earth sublattice͒ increases more rapidly than that aligned with the field, the net moment may point opposite to the applied magnetic field in a ferrimagneticlike state below the compensation temperature ͑T comp ͒.…”

“…Since the temperature dependence of compacted 20 nm La 1−x MnO 3 nanoparticles exhibits only a single magnetic transition and quite unusual M͑H͒ dependence ͑the negative mangnetization increases monotonically with increasing magnetic field͒, we believe that none of the above scenarios are applicable here. For further discussion we refer to Troyanchuk et al 8 and our 11 recent publications.…”

Influence of Nonstoichiometry on Magnetocaloric Effect in (La0.7Ca0.3)1 - xMn1+xO3

“…Therefore we have assumed that in our samples, as a result of a charge disproportionation reaction Mn 2+ ions having the largest ionic radius (r = 0.83 Å), which can occupy the A-position and, as it was synthesized in Ref. [18], can substitute a part of La ions. Since the vacancy space of the B site is smaller than that of the A site, we have assumed that the anion vacancies should also be at the B sites.…”