S. Takeshita

Relation between magnetic order and crystal structure in La1.875Ba0.125-yMyCuO4La1.875Ba0.125-yMyCuO4

We have performed zero-field muon spin relaxation (ZF-μSR)(ZF-μSR) measurements for La1.875Ba0.125-yMyCuO4La1.875Ba0.125-yMyCuO4(M=Sr(M=Sr, Ca)Ca). The magnetic ordering temperature TmTm determined by the appearance of the oscillation component decreases with increasing Sr/Ca concentration y xa0. The comparison between this result and our previous high-pressure μSRμSR study leads us to the conclusion that disorder at the A sites occupied by different ions induces or enhances the magnetic order. The degree of TmTm suppression for Ca substitution is much larger than that for Sr substitution. Since there is little difference in the A-site disorder between samples with the same value of y xa0, the large difference in TmTm cannot be explained only in terms of the A-site disorder. The striking difference is seen in the lattice constant along the c xa0-axis at room temperature. These suggest that the interplane distance is also important factor for TmTm.

Relation between magnetic order and crystal structure in La1.875Ba0.125-yMyCuO4

We have performed zero-field muon spin relaxation (ZF-μSR)(ZF-μSR) measurements for La1.875Ba0.125-yMyCuO4La1.875Ba0.125-yMyCuO4(M=Sr(M=Sr, Ca)Ca). The magnetic ordering temperature TmTm determined by the appearance of the oscillation component decreases with increasing Sr/Ca concentration y xa0. The comparison between this result and our previous high-pressure μSRμSR study leads us to the conclusion that disorder at the A sites occupied by different ions induces or enhances the magnetic order. The degree of TmTm suppression for Ca substitution is much larger than that for Sr substitution. Since there is little difference in the A-site disorder between samples with the same value of y xa0, the large difference in TmTm cannot be explained only in terms of the A-site disorder. The striking difference is seen in the lattice constant along the c xa0-axis at room temperature. These suggest that the interplane distance is also important factor for TmTm.

Relation between magnetic order and crystal structure in

We have performed zero-field muon spin relaxation (ZF-μSR)(ZF-μSR) measurements for La1.875Ba0.125-yMyCuO4La1.875Ba0.125-yMyCuO4(M=Sr(M=Sr, Ca)Ca). The magnetic ordering temperature TmTm determined by the appearance of the oscillation component decreases with increasing Sr/Ca concentration y xa0. The comparison between this result and our previous high-pressure μSRμSR study leads us to the conclusion that disorder at the A sites occupied by different ions induces or enhances the magnetic order. The degree of TmTm suppression for Ca substitution is much larger than that for Sr substitution. Since there is little difference in the A-site disorder between samples with the same value of y xa0, the large difference in TmTm cannot be explained only in terms of the A-site disorder. The striking difference is seen in the lattice constant along the c xa0-axis at room temperature. These suggest that the interplane distance is also important factor for TmTm.

Pressure Effect on Superconductivity and Magnetic Order in La2−xBaxCuO4 with x = 0.135

We have performed muon spin relaxation (μSR), resistivity and magnetic susceptibility measurements under high pressure for La2−xBaxCuO4 with x = 0.135. An oscillation component is observed in the μSR spectra at low temperatures under ambient pressure and pressure of 1.1 GPa. This result suggests that the low‐temperature tetragonal (LTT) structure is dispensable for the appearance of the magnetic order, since several experimental results indicate that the LTT structure vanishes at 1.1 GPa. The superconducting temperature Tc increases drastically with increasing pressure, while the magnetic ordering temperature Tm hardly depends on pressure. The suppression of Tc therefore has no correlation with Tm. However, by applying pressure, the magnetic ordering region is replaced by the superconducting region. We speculate that the suppression of Tc correlates with the magnetic volume fraction.

Muon Spin Relaxation Study of an Impurity Doped Antiferromagnetic Triangular Lattice with a 1D Ferromagnetic Chain: Ca3(Co1−xZnx)2O6

Measurements of magnetization and muon spin relaxation (μSR) have been carried out for the sample of Ca3 (Co1−xZnx)2O6 with a frustrated antiferromagnetic triangular lattice consisting of Ising ferromagnetic chains for the purpose of the investigation of Zn‐substitution effect on the frustrated system. The magnetic ordering temperature Tc1 determined from magnetization data is 22 K for x = 0.03, which is 3 K lower than that of the un‐doped sample. This implies the reduction of an inter‐chain interaction due to Zn‐substitution, In the μSR measurement in longitudinal fields, static magnetic order could not be observed even at 18 K below Tc1. By Zn‐substitution up to 3% in Ca3Co2O6, the magnetic frustration is not removed but rather enhanced due to the reduction of the exchange interaction in nearest and next nearest neighbors.

Effects of Pressure and Eu-Substitution on Superconductivity and Magnetism in RuSr2GdCu2O8

We have performed magnetization measurements under pressure in RuSr2Gd1−xEuxCu2O8 with various x. The magnetic transition temperature Tm, increases with increasing pressure in the samples with x=0.0 (RuGd1212) and 1.0 (RuEu1212) and increases with decreasing Eu concentration x (chemical pressure) in RuSr2Gd1−xEuxCu2O8. The increase of Tm is attributed to the enhancement of the Ru-Ru interaction due to the lattice contraction. The saturation magnetization Ms decreases with increasing pressure in the sample with x=1.0. It indicates that the Ru magnetic moments are canted, leading to a ferromagnetic net moment. The superconducting temperature Tc decreases in RuGd1212 and hardly changes in RuEu1212 with increasing pressure. However Tc decreases with increasing x in RuSr2Gd1−xEuxCu2O8. The former can be interpreted by the doping effect caused by pressure but the latter can not be explained in terms of the carrier change. It is suggested that larger Eu ion directly disturb the electronic states of the CuO2 planes.