JETP Letters: issues online

$The ,69Tm nuclear magnetic relaxation in ТтВа2СизОб+1 (χ 0.1 1.0, Δζ 0.1) and ТтВагСгиОв is studied at temperatures below 5 K. In all the samples, the Tm spin-lattice relaxation proceeds via intrinsic paramagnetic centers (PCs) like Cu2+ or copper-oxygen spin-polarized clusters. The experimental data for ТтВагСизОб+х support the idea of the structural (chemical) micro-phase separation in oxygen-deficient 123 compounds. Apparently, the samples with χ > 0.4 contain hole-poor non-superconducting regions enriched with PCs and hole-rich (PC-poor) superconducting regions. The volume fraction /„ of the PC-rich phase reaches a maximum value of 0.85 at χ — 0.4 and decreases monotonically at χ increasing (fn ~ 0.5, 0.3 and 0.25 at χ 0.5, 0.6 and 0.7, respectively). The Tm spin-lattice relaxation in the underdoped ТтВагС^Ов compound indicates that this sample, in contrast to oxygen-deficient ТтВагСизОбц-х, has a homogeneous composition. However, the Tm spin-spin relaxation measurements reveal two sorts of the Tm nuclear spins in Tml24 having different NMR spectra and different relaxation times ТгThe latter result gives an evidence for the electronic phase separation in СиОг planes. PACS: 61.72.Hh, 74.72.Bk, 74.80.Bj, 76.60.Lz$

The ^,69Tm nuclear magnetic relaxation in ТтВа2СизОб₊₁ (χ 0.1 1.0, Δζ 0.1) and ТтВагСгиОв is studied at temperatures below 5 K. In all the samples, the Tm spin-lattice relaxation proceeds via intrinsic paramagnetic centers (PCs) like Cu²+ or copper-oxygen spin-polarized clusters. The experimental data for ТтВагСизОб+х support the idea of the structural (chemical) micro-phase separation in oxygen-deficient 123 compounds. Apparently, the samples with χ > 0.4 contain hole-poor non-superconducting regions enriched with PCs and hole-rich (PC-poor) superconducting regions. The volume fraction /„ of the PC-rich phase reaches a maximum value of 0.85 at χ — 0.4 and decreases monotonically at χ increasing (fn ~ 0.5, 0.3 and 0.25 at χ 0.5, 0.6 and 0.7, respectively). The Tm spin-lattice relaxation in the underdoped ТтВагС^Ов compound indicates that this sample, in contrast to oxygen-deficient ТтВагСизОбц-х, has a homogeneous composition. However, the Tm spin-spin relaxation measurements reveal two sorts of the Tm nuclear spins in Tml24 having different NMR spectra and different relaxation times ТгThe latter result gives an evidence for the electronic phase separation in СиОг planes. PACS: 61.72.Hh, 74.72.Bk, 74.80.Bj, 76.60.Lz