Antiferromagnetic ordering states of oxygen-deficientNdBa2Cu3O

Optical study of RE 1 + x Ba 2 - x Cu 3 O 6 (RE = Nd, Sm) aaand YBa 2 Cu 3 O 6 in the mid infrared range

“…As shown in the inset, these absorptions in NdBa 2 Cu 3 O 6 at T = 530 K and in SmBa 2 Cu 3 O 6 at 420 K, persist above their Néel temperature [21] with no change of intensity, indicating that a magnetic origin is unlikely. In Figures 3a and 3b, the transmission measurements across ac-oriented platelets for the two orthogonal beam polarization modes are presented.…”

Magnetic ordering ofNd3+in single-crystalNdBa2<

“…17 The two main conclusions of that study were, ͑i͒ that high-purity crystals with stoichiometric cation ratios exhibit only one type of antiferromagnetic ordering of the Cu spins ͑the AFI phase͒, and ͑ii͒ that doping with excess Nd ions on the Ba site in otherwise chemically pure and stoichiometric crystals destabilizes the AFI phase at low temperatures, causing a reorientation of the Cu magnetic structure which proceeds via a noncollinear turn-angle phase into a second antiferromagnetic structure, the AFII phase. The AFI and AFII phases are distinguishable experimentally by the types of neutron-diffraction peaks observed: the AFI ordering gives rise to peaks with indices (hϩ1/2, kϩ1/2, l͒ referred to the crystallographic unit cell ͑h, k, and l are inte-gers͒, whereas the peaks from the AFII ordering are of the form (hϩ1/2, kϩ1/2, lϩ1/2).…”

“…The masses of the crystals were 42, 19, and 23 mg, respectively. NS(A) is one of the crystals that we used in our previous study of the Cu magnetic ordering 17 ͑where we referred to it as NdBa 2 Cu 3 O 6.09 ). These crystals were prepared from a BaO/CuO flux by the slowcooling method, similar to that described in Refs.…”

“…A subsequent refinement of the crystal structure of NS(A) from neutron four-circle diffraction data revealed the oxygen content to be xϭ0.09. 17 The reduction of crystal NS(B) was carried out at a temperature of 695°C in an oxygen atmosphere of 0.02 mbar for 138 h. We did not determine the oxygen composition directly, but with these reduction conditions we expect it to be close to xϭ0. 15.…”

Infrared transmission study of crystal-field excitations in Al- and Sr-dopedPr1+xBa2−xBarba1, Jandl2, Nekvasil3 et al. 2004Phys. Rev. BSelf Cite10070View full textAdd to dashboardCite

“…9 On the other hand, the inelastic neutron-scattering ͑INS͒ measurements show that the Nd/Ba substitution gives arise to an effective ferromagnetic coupling between the Cu 2ϩ ions of the Cu͑2͒O͑2,3͒ planes and the Cu͑1͒-O͑1͒ chains in Nd 1ϩx Ba 2Ϫx Cu 3 O 6ϩy . 10 Such magnetic reordering leads to a significant drop of T N in the nonstoichiometric compounds and is adverse to the formation of the superconducting state in the highly oxygenated materials.…”