High-field study of the magnetization in Ti doped ErCo(2) compound


Guillot M. , OENER Y.

JOURNAL OF APPLIED PHYSICS, vol.103, no.7, 2008 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 103 Issue: 7
  • Publication Date: 2008
  • Doi Number: 10.1063/1.2835478
  • Title of Journal : JOURNAL OF APPLIED PHYSICS

Abstract

The magnetization of powdered MgCu(2) structure-type intermetallic ErCo(1.95)Ti(0.05) was studied in the temperature range of 4.2-123 K in magnetic fields up to 23 T. A field-cooled magnetization jump at certain temperatures (T(C)) corresponds to a first-order magnetic phase transition from a paramagnetic to a ferrimagnetic state indicating cobalt moment formation. We observe that T(C) approach asymptotically T=50 K with the cooling field H(c). The magnetization above T(C) stays constant (temperature independent), but does not saturate even in the field of 23 T. The moment per unit formula was found to be approximately 7.25 mu(B) for this field. This behavior may be attributed to domain structures with the enhanced magnetocrystalline anisotropy field with titanium impurities. Magnetization versus magnetic field curves has also been recorded for both zero-field-cooled and field-cooled cases at various temperatures below and above T(C). These curves below T(C) show typical ferrimagnetic phase; in the intermediate temperature range of 34-50 K metamagnetism was observed and the sample becomes pure paramagnetic above 50 K. In addition, the resistivity measurement was performed in the temperature range of 4.2-273 K. A jumplike drop in the resistivity was observed at T(C). In comparison with that of ErCo(2), this transition temperature shifts to higher temperature as much as 2 K, consistent with the slight increase of the lattice parameter. This drop in resistivity becomes much deeper presumably due to the internal magnetoresistance within the large domains. Analysis of the resistivity data in terms of spin fluctuations including s-d electron scattering and electron-phonon interaction reveals that T(2) behavior becomes dominant in the temperature range of 34-50 K where the magnetization data exhibit metamagnetism. Therefore, we assert based on both magnetization and resistivity results that the spin-fluctuation effects are driving force for the cobalt moment formations. (C) 2008 American Institute of Physics.