Noncollinear phase of TbDy alloys

Journal Article · Tue May 01 00:00:00 EDT 1990 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.346037· OSTI ID:7123536

Foster, J J ^[1]; Cullen, J R ^[2]

---

1. Physics Department, The American University, Washington, DC 20016 (USA)
2. Solid State Branch (R45), Naval Surface Warfare Center, White Oak, Maryland 20903-5000 (USA)

Tb{sub {ital x}}Dy{sub 1{minus}{ital x}} is probably the simplest example of a magnetic system with competing anisotropy. Tb and Dy are both low-temperature easy-plane ferromagnets with well-characterized anisotropy energies, such that Tb moments prefer the {bold b} axis in the hcp structure, while Dy moments prefer the {bold a} axis. It has been predicted, by a two-subnetwork approximation, that the low-temperature phase of the alloys with {ital x} between 0.86 and 0.76 exhibits a nonsymmetry direction of magnetization, a noncollinear spin structure, and 12th-order anisotropy. However, the two-subnetwork approximation is suspect when used to describe magnetic structure in alloys near phase boundaries, such as those between the ferromagnetic and the noncollinear phase. Using a probability distribution for site occupation, we have calculated the fluctuations of the spin orientation and the spin-spin correlation function as a function of composition in the noncollinear phase. The mean-square fluctuation in spin orientation is proportional to ({ital x}{sub {ital b}}{minus}{ital x}){sup 1/2}, where {ital x}{sub {ital b}} is the critical concentration which separates the {bold b} axis ferromagnet from the noncollinear magnet. The average orientation also varies as ({ital x}{sub {ital b}}{minus}{ital x}){sup 1/2}. Therefore, the simple two-subnetwork model is not valid near the phase boundaries. In fact, we find that the fluctuations from the average site occupation increase the range of stability of the noncollinear phase.

• OSTI ID: 7123536
• Journal Information: Journal of Applied Physics; (USA), Vol. 67:9; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DYSPROSIUM ALLOYS
MAGNETIC PROPERTIES
TERBIUM ALLOYS
ANISOTROPY
CORRELATIONS
FLUCTUATIONS
QUANTITY RATIO
SPIN
SPIN ORIENTATION
ALLOYS
ANGULAR MOMENTUM
ORIENTATION
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
VARIATIONS
360104* - Metals & Alloys- Physical Properties