Observation of Cu-NMR of CuO₂ Plane Site in Antiferromagnetic YBa₂Cu₃O_6.1

抄録

New NMR signals in antiferromagnetic YBa₂Cu₃O_6.1 with the Néel temperature of T_N=410 K have been observed in the frequency range between 65 MHz and 125 MHz at the zero external field. In contrast to the nuclear quadrupole resonance (NQR) observed around 30 MHz, the newly observed signals are remarkably dominated by the appearance of the internal field generated by the antiferromagnetic ordering. According to neutron diffraction studies, there exists an antiferromagnetic moment of about 0.6 μ_B on the CuO₂ plane site. Accordingly, NMR signals are unambiguously assigned to the CuO₂ plane site and NQR signals around 30 MHz to the CuO chain site. This finding allows us to determine the magnetic phase diagram of YBa₂Cu₃O_7−y from a microscopic point of view.