Magnetic ordering in (Y1-xPrx)Ba2Cu 3O7 as evidenced by muon spin relaxation

Using the zero-field-muon-spin-relaxation (μSR) technique clear evidence has been found for antiferromagnetic ordering of Cu moments within the CuO planes of (Y1-xPrx)Ba2Cu3O 7. The Néel temperatures are approximately 285, 220, 35, 30, and 20 K for x=1, 0.8, 0.6, 0.58, and 0.54, respectively. For x=0.50 we observe a fast-relaxing component of the muon polarization in addition to a long-time tail, reminiscent of spin-glass behavior. This region of the phase diagram (0.5≤x≤0.54) corresponds to the existence of both superconductivity and magnetism. The fully developed local magnetic field for x>0.54 is found to be ∼16 mT, but decreases to ∼12 mT at T=17 K for the x=1 sample, presumably due to the onset of Pr-ion ordering. Magnetic ordering also occurs in PrBa2Cu3O6; the Néel temperature is ∼325 K.