The magnetic ordering of the Fe2P-type Tb6FeTe 2, Tb6CoTe2 Tb6NiTe2 and Er6FeTe2 phases (space group P6̄2m) has been investigated through magnetization measurement and neutron powder diffraction. Tb6FeTe2, Tb6CoTe2 and Tb 6NiTe2 demonstrate high-temperature ferromagnetic and low-temperature spin reorientation transitions, whereas Er6FeTe 2 shows antiferromagnetic transition, only. The Tb 6FeTe2 and Tb6NiTe2 phases show same high-temperature collinear ferromagnetic structure, whereas Tb 6FeTe2 is the commensurate non-collinear ferromagnet and Tb6NiTe2 is the canted ferromagnetic cone with K 1=[0, 0, ±3/10] and K2=[±2/9, ±2/9, 0] wave vectors at 2 K. The magnetic structure of Er6FeTe2 is a flat spiral with K1=[0, 0, ±1/10] at 2 K. The magnetic entropy change for Tb6NiTe2 is ΔSm=-4.86 J/kg K at 229 K for the field change Δμ0H=05 T. In addition, novel Fe2P-type Gd6FeTe2, Zr 6FeTe2, Hf6FeTe2, Dy 6NiTe2, Zr6NiTe2 and Hf 6NiTe2 phases have been obtained. © 2010 Elsevier Inc. All rights reserved.

R. Nirmala

Department Of Physics

Antiferromagnetic transition

FERROMAGNETIC STRUCTURES

Ferromagnets

Field change

High temperature

Low temperatures

Magnetic entropy change

Magnetic ordering

MAGNETICALLY ORDERED MATERIAL

Magnetization measurements

Magneto-caloric effects

P-type

rare earth intermetallics

Space Groups

Spin reorientation transitions

WAVE VECTOR

Antiferromagnetism

Erbium

Ferromagnetic materials

Gadolinium

hafnium

INTERMETALLICS

Magnetic properties

Magnetization

Neutron diffraction

Neutrons

Rare earth alloys

Rare earths

Zirconium

Ferromagnetism

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Solid State Chemistry

Several new Fe2P-type compounds (space group P62̄m) namely Ho6RuSb2, Ho6RuBi2, Ho 6RuTe2, Ho6MnTe2, Dy 6MnTe2, Dy6RuTe2, Er 6MnTe2 and Zr6CuBi2 were detected. The magnetic properties of the Fe2P-type Ho6RuSb 2, Ho6RuTe2, Ho6MnTe2, Dy6FeBi2, Dy6MnBi2 and Dy 6Mn0.33Fe0.67Bi2 compounds have been studied by means of bulk magnetization measurements. The magnetic structures of Ho6MnTe2 and Ho6FeBi2 were investigated by a neutron diffraction study in zero applied magnetic field. The structural and magnetic data for Ho-based Fe2P-type compounds are analyzed in order to arrive at an empirical rules for entire series of Fe 2P-type intermetallics. © 2011 Elsevier Ltd. All rights reserved.

Intermetallics

Structural and magnetic properties of Fe2P-type R 6TX2 compounds (R = Zr, Dy, Ho, Er, T = Mn, Fe, Co, Cu, Ru, Rh, X = Sb, Bi, Te)

The magnetic structure of the Fe2P-type R6CoTe2 phases (R=Gd-Er, space group P6-2m) has been investigated through magnetization measurement and neutron powder diffraction. All phases demonstrate high-temperature ferromagnetic and low-temperature transitions: TC=220 K and TCN=180 K for Gd6CoTe2, TC=174 K and TCN=52 K for Tb6CoTe2, TC=125 K and TCN=26 K for Dy6CoTe2, TCN=60 K and TN=22 K for Ho6CoTe2 and TCN∼30 K and TN∼14 K for Er6CoTe2. Between 174 and 52 K Tb6CoTe2 has a collinear magnetic structure with K0=[0, 0, 0] and with magnetic moments along the c-axis, whereas below 52 K it adopts a non-collinear ferromagnetic one. Below 60 K the magnetic structure of Ho6CoTe2 is that of a non-collinear ferromagnet. The holmium magnetic components with a K0=[0, 0, 0] wave vector are aligned ferromagneticaly along the c-axis, whereas the magnetic component with a K1=[1/2, 1/2, 0] wave vector are arranged in the ab plane. The low-temperature magnetic transition at ∼22 K coincides with the reorientation of the Ho magnetic component with the K0 vector from the collinear to the non-collinear state. Below 30 K Er6CoTe2 shows an amplitude-modulate magnetic structure with a collinear arrangement of magnetic components with K0=[0, 0, 0] and K1=[1/2, 1/2, 0]. The low-temperature magnetic transition at ∼14 K corresponds to the variation in the magnitudes of the MErK0 and MErK1 magnetic components. In these phases, no local moment was detected on the cobalt site. The magnetic entropy of Gd6CoTe2 increases from ΔSmag=-4.5 J/kg K at 220 K up to ΔSmag=-6.5 J/kg K at 180 K for the field change Δμ0H=0-5 T. © 2010 Elsevier Inc. All rights reserved.

Magnetic properties of Fe2P-type R6CoTe2 compounds (R=Gd-Er)

The magnetic structure of the ternary intermetallic compound Ho6FeTe2 (hexagonal Zr6CoAs2 structure type, a ternary ordered variant of the Fe2P-type; space group P over(6, ̄) 2 m, No 189) has been investigated by neutron diffraction and magnetization measurements. The neutron diffraction study shows that in between the temperatures TN ∼ 24 K and TC ∼ 8 K the magnetic moments of the Ho atoms adopt a flat helix ordering with elliptical envelope having a wave vector K = [0, 0, ∼1/9], the helix axis being coincident with the c-axis (with maximal magnetic moments of MH o1 = 6.5 (7) μB and MH o2 = 8.0 (7) μB, at 10 K). Below the TC ∼ 8 K the magnetic structure of Ho6FeTe2 changes to a ferromagnetic cone: superposed on the helix ordering within the basal plane a ferromagnetic ordering with K = [0, 0, 0] and moments pointing in the c-direction appears. At 2 K the total maximal magnetic moments amount to MH o1 = 9.1 (7) μB and MH o2 = 9.6 (7) μB with a ferromagnetic component on the H o1 site of Mc H o1 = 2.2 (5) μB and on the H O2 site of Mc H o2 = 5.2 (5) μB . No local moment was detected on the iron atomic site in this compound. Magnetization measurements confirm the first magnetic transition at ∼26 K and the second at ∼10 K. The magnetization vs. field data obtained at 2.5 K show soft ferromagnetic behavior, with a saturation magnetization of 7.9 μB/Ho3+. © 2010 Elsevier B.V. All rights reserved.

Journal of Alloys and Compounds

The magnetic ordering in the Ho6FeTe2 compound

Thermomagnetic properties near transitions of Tb6FeX2 (X=Sb, Bi)

Magnetic structure of the Zr6CoAs2-type Tb6FeBi2 compound

Magnetic structures of Zr6CoAs2-type Ho6FeSb2, Ho6CoBi2, Ho6FeBi2 and Ho6MnBi2 compounds

Magnetic properties of Fe2P-type Tb6FeTe2, Tb6CoTe2, Tb6NiTe2 and Er 6FeTe2 compounds

Journal	Journal of Solid State Chemistry
ISSN	00224596
Open Access	No