NMR and magnetic susceptibility in superconducting and antiferromagnetic Ga-based cuprates Y1-xCaxSr2Cu2GaO7 (0<=x<=0.3)

Magnetic susceptibility and NMR/NQR measurements were performed on Y1-xCaxSr2Cu2GaO7 (x=0, 0.1, 0.2, 0.3). The single phase samples annealed at 600 degrees C under oxygen pressure of 30 MPa are superconductors with T-c=35 K for x=0.2 and x=0.3. In spite of the presence of a small Curie-like term, we show that the spin susceptibility in the normal state increases with Ca doping and reaches the value chi(spin)approximate to 0.9 cm(3)/Cu-mole, which is comparable to other superconducting cuprates. From the observation of Cu zero-field resonance (AFNR) and susceptibility data the parent compound is classified as 2D antiferromagnet (T-N=387 K). The transition from antiferromagnetic insulator to superconductor occurs with increasing concentration of carriers, but extends over several tens percent of Ca, The superconductivity is significantly suppressed by increasing disorder within limits of solubility for Ca. The Ga NQR spectra are narrow in both antiferromagnetic and superconducting regimes, but heavily broadened in the intermediate spin-glass-like domain. From x=0 to x=0.3, the Cu-63 quadrupole frequency increases from 24 to 28 MHz due to the charge transfer resulting in superconductivity. Other EFG parameters are not markedly changed from those given in YSr2Cu2GaO7 by Pieper [Physica C190(1992)261].