Magnetic Order Of Cu Moments Research Articles

μSR study on multi-layered HgBa2Ca4Cu5Oy (Hg-1245) superconductor

We have carried out zero-field muon spin relaxation (ZF-μSR) measurements in multi-layered HgBa2Ca4Cu5Oy (Hg-1245) superconductor with Tc of 108 K. The variation of ZF-μSR time spectra from Gaussian-type to exponential-type behavior was observed with decreasing temperature below 60 K and the muon precessions were also observed below 45 K. These results indicate the appearance of a static magnetic order of Cu moments at muon sites below Tc. Compared with the results of NMR measurements, they suggest that this magnetic order is caused in three under-doped inner planes of five CuO2 planes in Hg-1245.

Positive muon spin rotation study on magnetic order in La 2−xM xCuO 4 (M=Ba,Sr) around x=0.12

Zero field muon spin rotation ( μSR) is applied to La 2−xM xCuO 4 (M=Ba, Sr) around x=0.12. Observation of the clear precession of the asymmetry pattern indicates the magnetic order of Cu-moments around x=0.12 where superconductivity is suppressed remarkably. Magnetic phase diagram is determined.

Competition of magnetic order and superconductivity investigated by positive muon spin rotation in La2?x M x CuO4 (M = Ba, Sr) aroundx=0.12

Muon spin rotation (μSR) is applied to La2−xBa x CuO4 aroundx=0.12 where the superconductivity (SC) is suppressed remarkably. The magnetic ordering of Cu-moments appears below 35 K in the narrow range ofx where a lattice instability from the low temperature orthorhombic (LTO) to the low-temperature tetragonal (LTT) structure exists. The present study suggests strongly that the magnetic ordering of Cu-moments is an important factor in the suppression of high-Tc superconductivity aroundx=0.12 in La2−xBa x CuO4. Similar results are obtained for the La2−xSr x CuO4 and La2−x−ySr x Nd y CuO4 systems.

Magnetic Order of Cu-Moments in La2-xBaxCuO4aroundx=0.12 Observed by Positive Muon Spin Rotation

Positive muon spin rotation (µ + SR) is applied to La 2- x Ba x CuO 4 around x =0.12, where superconductivity is suppressed remarkably. The magnetic ordering of Cu-moments appears below 35 K in the narrow range of 0.11≦ x ≦0.135, where the transition from the low-temperature orthorhombic (LTO) to the low-temperature tetragonal (LTT) structure exists. The present study suggests strongly that the magnetic ordering of Cu-moments plays an important role in the suppression of the high- T c superconductivity around x =0.12 in La 2- x Ba x CuO 4 .

Superconducting, electronic and magnetic anomalies due to structural transition around x=0.12 in La 2−xBa xCuO 4

From anomalies of the heat capacity and the thermal expansion, the structural phase boundary of the LTT-LTO transition is determined in the narrow range around x=0.12 of La 2−xBa xCuO 4, where superconductivity is suppressed remarkably. The widely-spread CuNQR spectra and the decay of the asymmetry parameter of μSR are indicative of the magnetic order of Cu moments in the LTT phase where the induced charge transfer between Cu and O atoms causes the localization of the electronic state and the increase of magnetic moments at the Cu site.

Mössbauer study of magnetic ordering in57Co-doped Eu2CuO4 and Gd2CuO4

Zeeman splitting of Mossbauer spectra of57Co doped into Eu2CuO4 and Gd2CuO4 indicates magnetic ordering of Cu moments for temperatures below about 150 K in Eu2CuO4 and below about 200 K in Gd2CuO4.

Nuclear heat capacity due to the static Cu-magnetic moments in the superconducting La 2-x Sr x CuO 4

Abstract The heat capacity of La 2-x Sr x CuO 4 for 0 63/65 Cu nuclei, from which we obtain the x-dependence of the hyperfine field of Cu nuclei. The result shows the static magnetic order of Cu-moments in the superconducting La-system.

Evidence of magnetic order of Cu moments in the superconducting and normal region of La2−Sr CuO4: Observation of Cu-NQR for 0.12≦x≦0.40

The observation of Cu-NQR in La2−xSrxCuO4 revealed that the spectra were splitted into two peaks at low temperatures and that its separation decreased with increasing x. This fact indicates that the well-defined hyperfine field due to magnetic ordering of Cu moments exists in the superconducting and normal metallic regions. The nuclear spin-lattice relaxation rate, 1/T1 of the Cu spectra is suppressed apparently by the superconducting energy gap for x≦0.20, while its temperature dependence obeys the Korringa relation for the normal region of x≧0.25. The nuclear spin-spin relaxation rate, 1/T2 increases proportionally with increasing hyperfine field, indicating the dominant indirect unclear spin coupling via virtual excitation of antiferromagnetic spin waves. The coexistence of superconductivity and the magnetic order of Cu d-electrons with a tiny moment is demonstrated by the NQR study in the La-Sr-Cu-O system

Antiferromagnetism and superconductivity in the presence of Ho moments in HoBa2Cu3Ox.

Using the zero-field muon-spin-relaxation technique, we have observed a long-range magnetic ordering of Cu moments in a tetragonal insulator $\mathrm{Ho}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{x}$ with $x\ensuremath{\sim}6.2$. The magnitude of the internal field and its temperature dependence were found to be similar to those of Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.2}$. At temperatures below 3 K, freezing of the Ho magnetic moment was observed as in a 90-K superconductor Ho${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.9}$. These results imply that the effect of the magnetic rare-earth ${\mathrm{Ho}}^{3+}$ ions on the antiferromagnetism of the Cu ions is small, suggesting a relatively weak interaction between the Ho ions and the electrons in two-dimensional Cu-O planes.