Unusual magnetism of Er0.75Dy0.25Al2

R. Nirmala, Ya. Mudryk, V. K. Pecharsky, and K. A. Gschneidner, Jr.
Phys. Rev. B 76, 014407 – Published 6 July 2007

Abstract

dc magnetization, ac magnetic susceptibility, magnetic relaxation, electrical resistivity and x-ray powder-diffraction studies of Er0.75Dy0.25Al2 compound have been carried out in the temperature range of 5300K. The compound orders ferromagnetically at 25K, followed by another transition at 10K. This transition at 10K is marked by a significant hysteresis in low applied fields in zero-field-cooled and field-cooled magnetization data. The saturation magnetic moment is 8.24μBR3+ at 2K in a 70kOe field, indicating the presence of strong crystalline electric fields. A signature of weak glassy behavior is observed below 25K in frequency dependent ac magnetic susceptibility measurements. This observation is attributed to competing single-ion anisotropies of Dy3+ and Er3+ ions that are statistically distributed in the lattice, thus creating large positional entropy. The paramagnetic phase of this compound includes a narrow region of Griffiths-phase-like behavior, signified by the presence of short-range ferromagnetic correlations. A long-time logarithmic relaxation of magnetization has been observed in the ferromagnetically ordered state. The electrical resistivity shows a slope change near 25K and also a drop at 10K. The electrical resistivity in the ferromagnetic state follows T2 law, indicating the dominant role of magnon scattering. The magnetoresistance is 13% at 25K in a 30kOe field. The role of quadrupolar interactions and magnetoelastic coupling in producing a possible structural distortion at 10K has been considered and x-ray-diffraction studies were carried out down to 5K. No structural change has been detected at 10K, and hence the quadrupolar coupling between the rare-earth ions via the lattice should be weak, whereas direct higher-order Coulombic interactions may prevail.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
3 More
  • Received 27 February 2007

DOI:https://doi.org/10.1103/PhysRevB.76.014407

©2007 American Physical Society

Authors & Affiliations

R. Nirmala and Ya. Mudryk

  • Materials and Engineering Physics Program, Ames Laboratory of the United States Department of Energy, Iowa State University, Ames, Iowa 50011-3020, USA

V. K. Pecharsky* and K. A. Gschneidner, Jr.

  • Materials and Engineering Physics Program, Ames Laboratory of the United States Department of Energy, Iowa State University, Ames, Iowa 50011-3020, USA and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011-2300, USA

  • *Corresponding author. Electronic address: vitkp@ameslab.gov

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 76, Iss. 1 — 1 July 2007

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×