Temperature and field dependence of the magnetic properties of Nd $\mathsf{_{2-x}}$ Ce $\mathsf{_{x}}$ CuO $\mathsf{_4}$

We have investigated the magnetic ordering of Nd 2-x Ce x CuO 4 for x=0, 0.09, 0.13, 0.15 and 0.18 by neutron diffraction at low temperatures down to 33 mK and under magnetic field up to 5 tesla applied along [1,-1,0] crystallographic direction. At zero applied magnetic field Cu magnetic sublattice orders at $T_{N} \approx 250$ , 210, 130 and 105 K for x=0, 0.09, 0.13, 0.15, respectively. No long range magnetic order of the Cu could be detected for x=0.18. The magnetic order of Nd was found in all samples, with a gradual increase of the polarized magnetic moment with decreasing temperature, saturating around 1 K. Hyperfine induced nuclear polarization of the Nd nuclear spin has been observed below about 400 mK for samples with x=0, 0.13, 0.15 and 0.18. Field variation of the intensities of the principal and superstructure reflections of Nd 2-x Ce x CuO 4 at millikelvin temperatures shows a field-induced second-order double- k to single- k phase transition at H c =0.75 and 0.56 tesla for samples with x=0 and 0.15, respectively at T=50 mK. We have also investigated the polarization of the Nd electronic sublattice due to the field of the Cu sublattice by the element specific X-ray resonant magnetic scattering investigation with synchrotron radiation. Copyright Springer-Verlag Berlin/Heidelberg 2004