Magnetic structure and magnetization process of NdCo12xVx

G. H. Rao, W. F. Liu, Q. Huang, Z. W. Ouyang, F. W. Wang, Y. G. Xiao, J. W. Lynn, and J. K. Liang
Phys. Rev. B 71, 144430 – Published 29 April 2005

Abstract

NdCo12xVx (2.2x2.6) crystallizes in the ThMn12-type structure and exhibits an unusual jump in the magnetization at a critical field BC that decreases with increasing V content. It was intriguing that the magnetization of the bulk samples below BC was very close to that of YCo12xVx with the same V content. To investigate the nature of the magnetic order in these materials we have carried out powder neutron diffraction measurements as a function of temperature and magnetic field on the NdCo9.5V2.5 composition. In zero field we find that both the Nd and Co ions have substantial ordered moments (2.9 and 0.4μB, respectively) at low temperature (4K), with the moments coupled ferromagnetically (TC=180K) and aligned along the c axis. On a loose powder an applied field of 4to7T rotates the particles so the c axis aligns with the field, indicating a strong uniaxial anisotropy that renders the system Ising-like. However, we find the same in-field magnetic structure and essentially the same values for the saturated magnetic moments as those in zero field. Magnetization data on magnetically prealigned samples reveal that for fields applied parallel to the (easy) c axis the magnetization saturates below 0.5T at a magnitude that is in very good agreement with the moments determined from neutron diffraction. For fields applied perpendicular to the c axis, on the other hand, the magnetization data show a two-plateau behavior, explaining the original magnetization data on randomly oriented powders. The strong dependence of the magnetization on the direction of the applied magnetic fields indicates an occurrence of the first-order magnetization process due to the competing magnetocrystalline anisotropies of the Nd and the Co sublattices and of the higher-order terms of the anisotropy energy.

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  • Received 21 September 2004

DOI:https://doi.org/10.1103/PhysRevB.71.144430

©2005 American Physical Society

Authors & Affiliations

G. H. Rao1, W. F. Liu1, Q. Huang2, Z. W. Ouyang1, F. W. Wang1, Y. G. Xiao1, J. W. Lynn2, and J. K. Liang1,3

  • 1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China
  • 2NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8562, USA
  • 3International Center for Materials Physics, Academia Sinica, Shenyang 110016, People’s Republic of China

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Issue

Vol. 71, Iss. 14 — 1 April 2005

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