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Title: Anisotropy induced anomalies in Dy 1$-$xTb xAl 2

Abstract

The Dy 1$-$xTb xAl 2 alloys have been investigated by X-ray powder diffraction, heat capacity, and magnetic measurements. All samples exhibit cubic Laves phase crystal structure at room temperature but at T C, DyAl2 and TbAl 2 show tetragonal and rhombohedral distortions, respectively. First order phase transitions are observed below T C (at the spin-reorientation transition, T SR) in the alloys with 0.15 ≤ x ≤ 0.35. These transitions are signified by sharp heat capacity peaks and corresponding anomalies in the magnetization and ac magnetic susceptibility data. The observations are interpreted by taking into consideration the differences in easy magnetization directions of DyAl 2 and TbAl 2. Due to the competing magnetic structures, the anisotropy-related instability and magnetic frustrations are prominent in the Dy 1$-$xTb xAl 2 alloys at certain concentrations resulting in the first order transitions.

Authors:
 [1];  [2];  [1];  [1];  [3];  [3]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  2. (United States) . Dept. of Physics
  3. Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1355404
Report Number(s):
IS-J-9258
Journal ID: ISSN 2050-7526; JMCCCX
Grant/Contract Number:
AC02-07CH11358
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. C
Additional Journal Information:
Journal Volume: 5; Journal Issue: 4; Journal ID: ISSN 2050-7526
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Khan, M., Miami Univ., Oxford, OH, Pathak, A. K., Mudryk, Y., Gschneidner, Jr., K. A., and Pecharsky, V. K. Anisotropy induced anomalies in Dy1$-$xTbxAl2. United States: N. p., 2017. Web. doi:10.1039/C6TC05384J.
Khan, M., Miami Univ., Oxford, OH, Pathak, A. K., Mudryk, Y., Gschneidner, Jr., K. A., & Pecharsky, V. K. Anisotropy induced anomalies in Dy1$-$xTbxAl2. United States. doi:10.1039/C6TC05384J.
Khan, M., Miami Univ., Oxford, OH, Pathak, A. K., Mudryk, Y., Gschneidner, Jr., K. A., and Pecharsky, V. K. Mon . "Anisotropy induced anomalies in Dy1$-$xTbxAl2". United States. doi:10.1039/C6TC05384J. https://www.osti.gov/servlets/purl/1355404.
@article{osti_1355404,
title = {Anisotropy induced anomalies in Dy1$-$xTbxAl2},
author = {Khan, M. and Miami Univ., Oxford, OH and Pathak, A. K. and Mudryk, Y. and Gschneidner, Jr., K. A. and Pecharsky, V. K.},
abstractNote = {The Dy1$-$xTbxAl2 alloys have been investigated by X-ray powder diffraction, heat capacity, and magnetic measurements. All samples exhibit cubic Laves phase crystal structure at room temperature but at TC, DyAl2 and TbAl2 show tetragonal and rhombohedral distortions, respectively. First order phase transitions are observed below TC (at the spin-reorientation transition, TSR) in the alloys with 0.15 ≤ x ≤ 0.35. These transitions are signified by sharp heat capacity peaks and corresponding anomalies in the magnetization and ac magnetic susceptibility data. The observations are interpreted by taking into consideration the differences in easy magnetization directions of DyAl2 and TbAl2. Due to the competing magnetic structures, the anisotropy-related instability and magnetic frustrations are prominent in the Dy1$-$xTbxAl2 alloys at certain concentrations resulting in the first order transitions.},
doi = {10.1039/C6TC05384J},
journal = {Journal of Materials Chemistry. C},
number = 4,
volume = 5,
place = {United States},
year = {Mon Jan 02 00:00:00 EST 2017},
month = {Mon Jan 02 00:00:00 EST 2017}
}

Journal Article:
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  • The magnetic properties of Dy/sub x/Tb/sub 1-x/FeO/sub 3/ (x=0.75, 0.5, 0.25, 0) single crystals were studied. On the basis of the data obtained in this study, the maximum value of the anisotropy factor K/sup a/b/sub Fe/ in the crystallographic ab-plane of the iron sublattice is now calculated and it is shown that K/sup a/b/sub Tb/ is much larger than K/sup a/b/sub Dy/, while K/sup a/c/sub Tb/ is small.
  • Magnetization curves, Curie temperature, and lattice constants of twin-free [111]-oriented single-crystal Tb{sub 0.27}Dy{sub 0.73}(Fe{sub 1{minus}{ital x}}Al{sub {ital x}}){sub 2} ({ital x}=0, 0.1) were investigated. It was observed that with the substitution of Al for Fe, Curie temperature and magnetocrystalline anisotropy decrease, and lattice constants increase. It is shown from the curves of magnetic moment versus temperature that the anisotropy compensation temperature of Tb{sub 0.27}Dy{sub 0.73}(Fe{sub 0.9}Al{sub 0.1}){sub 2} is 280 K, which is higher than 260 K of Tb{sub 0.27}Dy{sub 0.73}Fe{sub 2}. Besides, the saturation magnetostriction {lambda}{sub 111} of Tb{sub 0.27}Dy{sub 0.73}(Fe{sub 0.9}Al{sub 0.1}){sub 2} was measured by using strainmore » gauge method. The result indicates that {lambda}{sub 111} increases from 1.01{times}10{sup {minus}3} to 1.54{times}10{sup {minus}3} as the compressive stress is increased from 0 to 12 MPa, and that the maximal {ital D}{sub 33}({ital d}{lambda}/{ital dH}) is about 1.0. It is the first time to present the experimental data of the twin-free [111]-oriented single crystal of Tb{sub 0.27}Dy{sub 0.73}(Fe{sub 0.9}Al{sub 0.1}){sub 2}. {copyright} {ital 1996 American Institute of Physics.}« less
  • The anisotropy constant K/sub 1/ in the intermetallic compounds Y/sub 2/Co/sub 17/, Dy/sub 2/Co/sub 17/, and two pseudobinaries Y/sub 2//sub x/Dy/sub 2//sub 1-x/Co/sub 17/ (x=1/3,2/3) is determined over the temperature range 77.4--383 degreeK. This constant is obtained by fitting the measured magnetization curves to the equation for magnetization along the hard axis derived by minimizing the sum of the magnetocrystalline anisotropy energy and the magnetic potential energy. All of the four compounds have an easy basal plane over the entire temperature range. The two pseudobinaries Y/sub 2///sub 3/Dy/sub 4///sub 3/Co/sub 17/ and Y/sub 4///sub 3/Dy/sub 2///sub 3/Co/sub 17/ develop basal-planemore » anisotropy at low temperatures. The contribution of the Dy sublattice to the anisotropy constant and the saturation magnetization is treated for single-ion behavior.« less
  • The magnetic phase diagram of the crystalline dilute magnets Tb{sub {ital x}}Y{sub 1{minus}{ital x}}Al{sub 2} has been determined, showing spin-glass reentrance into a quasiferromagnetic (QF) phase for {ital x}{sub {ital t}} {ge} 0.27 and {ital T} {le} 8.6 K, the tricritical point. The effective percolation limit is {ital x}{sub {ital p}}=0.16 with a critical line separating the paramagnetic and QF regimes of exponent {phi}{sub {ital p}}=1.1. No signs of saturation magnetization are found, nor of any clear divergence of the dc zero-field susceptibility. On the spin-glass side of these series ({ital x}{lt}0.27), the order parameters {ital q} (frozen local moment)more » and {Delta} (irreversibility parameter) have been determined from the field- and zero-field-cooled measured susceptibilities.« less
  • From magnetization ({ital M}) and magnetostriction ({lambda}) measurements as a function of magnetic field and stress, the temperatures of anisotropy compensation, {ital T}{sub {ital m}}, for technologically important Tb{sub {ital x}}Dy{sub 1{minus}{ital x}}(Fe{sub 1{minus}{ital y}}T{sub {ital y}}){sub 1.9} (T=Co,Mn (0.3{le}{ital x}{le}0.5) (0{le}{ital y}{le}0.3)) were determined. Measurements of {ital M} and {lambda} encompassing {ital T}{sub {ital m}} were made under compressive stresses from 8.8 to 36 MPa and for temperatures from {minus}196 to +130 {degree}C. In agreement with earlier measurements, {ital T}{sub {ital m}} decreases with increasing Tb. Substitution of Mn for Fe for fixed {ital x} also decreases {ital T}{submore » {ital m}}. In contrast with these observations is the {ital increase} of the anisotropy compensation temperature with the replacement of Fe by small amounts of Co. In the cases of both (1) increasing Tb content and (2) increasing Co content, the Curie temperature {ital T}{sub {ital C}} increases, yielding, in general, a higher magnetic moment and saturation magnetostriction of these alloys. Thus, compensation at a given temperature may be obtained in an improved class of Laves phase compounds, R{sup (1)}{sub {ital x}}R{sup (2)}{sub 1{minus}{ital x}}(Fe{sub 1{minus}{ital y}}Co{sub {ital y}}){sub 2}, where rare earths R{sup (1)} and R{sup (2)} are, for example, Tb and Dy.« less