Superexchange interaction and magnetic moment in antiferromagnetic high-Tc cuprate superconductors

High-TcSuperconductivity and Antiferromagnetism in Multilayered Copper Oxides –A New Paradigm of Superconducting Mechanism–

“…[55][56][57][58][59][60][61][62] To obtain more underdoped samples of the Hg1245 system, as-prepared samples in nearly optimally doped region [Hg1245(OPT)] were annealed in a quartz tube with Cu powder or in Ar gas atmosphere for more than several hundreds of hours. 39,46,62) In Ba 2 Ca nÀ1 Cu n O 2n (F y -O 1Ày ) 2 , the substitution of oxygen (O À2 ) for apical fluorine (F À1 ), i.e., a decrease in nominal fluorine content (y), results in the doping of holes into CuO 2 layers, increasing T c . [57][58][59][60][61] Although the real apical fluorine F À1 content may deviate slightly from the nominal one, T c and carrier density (p) can be tuned by changing the nominal content y in this series, which provides an opportunity to investigate the characteristics of CuO 2 layers over a wide p range systematically in the homologous series of n-layered cuprates.…”

“…Figures 6(a)-6(g) respectively show the layer-dependent physical properties unraveled by site-selective NMR studies of the following n ¼ 5 compounds: 46,51) Hg1245 38,43) and Cu1245(OVD) (T c ¼ 90 K). 37) The temperature (T ) dependences of K ab s ðT Þ are shown in the lower panel of the figures.…”

“…Thus, we discuss here a ground-state phase diagram of a 49) and YBCO 6þx , 125,126) n ¼ 3:0223F, 44,50) n ¼ 4:0234F, 41,44,45) and n ¼ 5:M1245. 38,39,43,46,51) p c ðnÞ, at which an AFM order collapses, increases from p c ðnÞ $ 0:075 to 0.08 to 0.10 as n increases from 3 to 4 to 5, respectively. The result on n ¼ 8 compound has revealed that p c ð8Þ does not reach 0.14 even when an interlayer magnetic coupling is enhanced, which is also deduced from the fact that M AFM decreases to zero in the range of p c ðM AFM ¼ 0Þ 0:14 (see Fig.…”

“…Site-selective nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) studies are unique tools for differentiating layer-dependent electronic characteristics microscopically. [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] One of the remarkable features and advantages of multilayered cuprates is that the CuO 2 layers are very flat and homogeneously doped, which have been ensured by the narrowest NMR linewidth to date among the very high quality cuprates investigated thus far (for example, see Fig. 4).…”

“…[38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] The intrinsic phase diagram possesses the following features: The AFM metallic state is robust and coexists uniformly with the HTSC at a single CuO 2 plane in a region extending up to the optimally doped one. The critical carrier density p c at which the AFM order collapses decreases from 0.10 to 0.08 to 0.075 as the interlayer magnetic coupling becomes weaker when decreasing from n ¼ 5 to 4 to 3, respectively.…”