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 CuO₄ 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 , 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 CuO₄ 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.Received: 9 April 2004, Published online: 14 December 2004PACS: 75.25. + z Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source X-ray scattering, etc.)T. Chatterji: Has changed his surname from Chattopadhyay to Chatterji.     

Magnetic order in RCr\mathsf{_{2}}Si\mathsf{_{2}} intermetallics

The magnetic structure and ordering temperatures of three intermetallic compounds which crystallize in the tetragonal ThCr₂Si₂ structure, TbCr₂Si₂, HoCr₂Si₂ and ErCr₂Si₂, have been determined by neutron diffraction, differential scanning calorimetry and magnetization measurements. The Cr-sublattice orders anti-ferromagnetically with Néel temperatures of 758 K for TbCr₂Si₂, 718 K for HoCr₂Si₂ and 692 K for ErCr₂Si₂. Chromium atoms located at 4d crystallographic sites are aligned anti-parallel along the c-axis, with G_ZCr magnetic modes. In contrast with metallic bcc Cr, the refined room temperature value of the ordered Cr moment is anomalously large for all three compounds. No long range magnetic order of the R sublattice in TbCr₂Si₂ and HoCr₂Si₂ is observed, whilst the Er sublattice in ErCr₂Si₂ orders independently of the Cr sublattice below 2.4 K with moments ferromagnetically aligned in the basal plane.Received: 4 November 2003, Published online: 30 January 2004PACS: 75.25. + z Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source X-ray scattering, etc.) - 75.30.Cr Saturation moments and magnetic susceptibilities - 75.50.Ee Antiferromagnetics