Magnetism of Ho_1-xTb_xAl₂ alloys: Critical dependence of a first-order transition on Tb concentration

Journal Article · Tue Dec 27 00:00:00 EST 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.84.214437· OSTI ID:1098492

Khan, Mahmud; Mudryk, Ya.; Gschneidner, K. A.; Pecharsky, V. K.

HoAl₂ exhibits a first-order spin reorientation transition at 20 K, which is manifested as a sharp peak in the heat capacity. When Ho is partially replaced by only 5% of Tb, the sharp heat-capacity peak in Ho_1-xTb_xAl₂ (x = 0.05) disappears, and then reappears again for x ≥ 0.07. For x = 0.05, the anomaly corresponding to the spin reorientation transition is barely seen in the heat capacity, but as x exceeds 0.07 the weak anomaly transforms to a sharp peak. The spin reorientation transition temperature increases to 29 K for x = 0.05, and as x increases further the transition shifts to lower temperature and returns to ~20 K for x = 0.25. The transition is no longer observed when x exceeds 0.60. Temperature-dependent x-ray powder-diffraction data confirm the first-order nature of the spin reorientation transition for the alloy with x = 0.40, and indicate that the compound retains the room-temperature cubic structure within the sensitivity of the technique. Experimental observations are discussed considering the easy magnetization directions of HoAl₂ and TbAl₂.

• Sponsoring Organization: USDOE
• OSTI ID: 1098492
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 21 Vol. 84; ISSN 1098-0121; ISSN PRBMDO
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English