The results of low temperature magnetization measurements carried out on the Dy0.73Tb0.27Fe2-xCox system and their hydrogenated compounds are presented. Low temperature (12 K) magnetization data reveals a large increase in anisotropy in the hydrogenated compounds, attributed to a modification in crystalline electric field effects as a result of the orientational ordering of hydrogen atoms in the lattice. The discrete step-wise increase in magnetization upto a field of 2 kOe in the parent alloys and the hydrogenated compounds is attributed to spin-flip metamagnetism. © 1998 Elsevier Science Ltd. All rights reserved.

G. Markandeyulu

Department Of Physics

S. Kishore

K. V.S. Rama Rao

chemical modification

Crystal lattices

Crystal orientation

Crystalline materials

Electric field effects

Hydrogen

Hydrogenation

INTERMETALLICS

magnetic anisotropy

Magnetism

Magnetization

temperature measurement

LAVE PHASE COMPOUNDS

SLIP-FLIP METAMAGNETISM

Dysprosium compounds

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IIT Madras

Spin–flip metamagnetism in the laves phase compounds Dy0.73Tb0.27Fe2−xCoxHn

Solid State Communications

Magnetization and magnetoresistance studies have been carried out on Ho0.85Tb0.15Mn2 and Ho0.85Tb 0.15Fe2. The saturation magnetization of Ho 0.85Tb0.15Mn2 is found to be large compared to Ho0.85Tb0.15Fe2. A large negative magnetoresistance of 27% was observed for Ho0.85Tb 0.15Mn2 around the ordering temperature. In the paramagnetic region, a positive magnetoresistance at lower magnetic fields and negative magnetoresistance is at higher magnetic fields have been observed for Ho0.85Tb0.15Mn2. A positive magnetoresistance of 3.5% with a step-like behavior has been observed for Ho0.85Tb 0.15Fe2 at 5 K. © 2005 Elsevier B.V. All rights reserved.

Physica B: Condensed Matter

Magnetic and electrical properties of Ho0.85Tb 0.15Mn2 and Ho0.85Tb0.15Fe2

Magnetoresistance (Δρ ρ) studies have been carried out on the C15-type cubic Laves phase Ho0.85Tb0.15Mn2-xFex (x=0, 0.25, 0.5, 1, and 2) compounds up to a magnetic field of 90kOe at temperatures 5, 30, and 100K. The lattice parameters were found to decrease with increasing x. The Curie temperature is found to increase with increasing x from 30to680K, which is attributed to the net increase in the exchange splitting of the spin-up and spin-down bands. A maximum value of Δρ ρ of -27% was observed for Ho0.85Tb0.15Mn2 around the ordering temperature. This is explained on the basis of nearest Mn-Mn critical distance. A positive magnetoresistance, increasing in a discontinuous manner with increasing field, due to the dependence of scattering of conduction electrons on large magnetoelastic interactions, was observed at 5K in Ho0.85Tb0.15Fe2. © 2005 The American Physical Society.

Physical Review B - Condensed Matter and Materials Physics

Magnetoresistance studies of Ho0.85Tb0.15Mn2-xFex (x=0, 0.25, 0.5, 1, and 2)

The structural, electrical and magnetic properties of Dy 0.73Tb0.27Fe2-xMnx [x=0, 0.25, 0.5 and 1] have been investigated through X-ray diffraction studies and magnetization, Curie temperature and electrical resistivity measurements. The lattice parameter is found to increase with increasing Mn concentration. The saturation magnetization increases with increasing Mn concentration. The Curie temperature is found to decrease with increasing x, which is attributed to the net decrease in the exchange splitting of the spin-up and spin-down bands. Spin fluctuations have been observed in Dy0.73Tb0.27FeMn. All the materials are seen to exhibit metallic behavior and the contributions to the resistivity are discussed as due to the scattering due to magnons, s-d interactions and phonons, depending on the temperature. © 2004 Elsevier B.V. All rights reserved.

Journal of Magnetism and Magnetic Materials

Magnetic and electrical properties of Dy0.73Tb 0.27Fe2-xMnx [x=0, 0.25, 0.5 and 1]

The structural, electrical and magnetic properties of Ho 0.85Tb0.15Fe2Bx (x = 0,0.05,0.1,0.15) have been carried out through X-ray diffraction, electrical resistivity and magnetization measurements. All the alloys are found to crystallize in C15-type cubic Laves phase structure. It is observed that the lattice parameter is found to increase with increasing boron concentration, which may be due to the occupation of boron at interstitial sites. The magnetization and Curie temperature are found to be constant with the increase in x. The temperature variation of electrical resistivity shows a metallic behavior with an increase in resistivity with increasing boron concentration. The resitivity behavior is explained on the basis of electron-magnon scattering at low temperatures and electron-phonon scattering at high temperatures. © 2004 Elsevier B.V. All rights reserved.

Structural, electrical and magnetic properties of Ho0.85Tb 0.15Fe2Bx

The structural, magnetic and electrical properties of Ho 0.85Tb0.15Fe2Mnx (x = 0-0.15) have been characterized through X-ray diffraction, Curie temperature and electrical resistivity measurements. All the alloys are found to crystallize in C15-type cubic Laves phase structure. It is observed that the lattice parameter increases with increasing Mn concentration. The Curie temperature is found to decrease with increasing x, which is attributed to the net decrease in the exchange splitting of the spin-up and spin-down bands. All the materials are seen to exhibit metallic behavior with a decrease in the slope of ρ versus T curve near the Curie temperature. The resistivity behavior is explained on the basis of s-d scattering mechanism and electron-phonon interaction. Spin fluctuations have been observed through Curie temperature and resistivity measurements. © 2003 Elsevier B.V. All rights reserved.

Magnetic and electrical properties of Ho0.85Tb 0.15Fe2-xMnx (0, 0.5, 1.0, 1.5)

A top-loading sample chamber tube, radiation shield and the vacuum shroud for interfacing a closed-cycle helium refrigerator for use with a vibrating sample magnetometer have been designed and fabricated. A lowest temperature of 12 K is achieved at the sample. The eddy current effects in the copper sample chamber tube are minimized by the use of an electrically insulating epoxy resin medium. The sample temperature is measured by a GaAlAs diode sensor attached on a sensor mount which is inserted into the sample zone and kept in helium atmosphere. The vibrations of the cryocooler's cold head are isolated from the vibrating sample magnetometer's head by incorporating a bellows. Using this facility the magnetic transitions of some rare earth elements have been measured and compared with the literature data. © 1998 IOP Publishing Ltd.

Measurement Science and Technology

Interfacing of a closed-cycle helium refrigerator to a vibrating sample magnetometer for low-temperature (12-300 K) magnetization studies

The results of 57Fe Mössbauer investigations carried out on the hydrogenated compounds of Dy0.73Tb0.27Fe1.5Co0.5 are presented. A change in the temperature range of the [1 0 0]-[1 1 1] spin reorientation transition from 200-290 K in Dy0.73Tb0.27Fe1.5Co0.5 to 100-150 K in Dy0.73Tb0.27Fe1.5Co0.5H 0.5 is attributed to changes in the crystalline electric field (CEF) effects resulting from the increase in rhombohedral distortions due to the orientational ordering of hydrogen atoms in the lattice. The variations in hyperfine field and isomer shift are also discussed. © 1997 Elsevier Science Ltd.

57FE mössbauer investigations on the hydrogenated compounds of Dy0.73Tb0.27Fe1.5Co0.5

Dy0.73Tb0.27Fe2 - xCox (x = 0.5, 1.0, 2.0) and their hydrides (hydrogen concentration n = 1.0) are found to crystallize in C15 cubic Laves phase. While the x = 0.5 and 1.0 materials and their hydrides have Curie temperatures above 300 K, the x = 2.0 material and its hydride are paramagnetic at 300 K. The magnetization measurements carried out at 300 K showed large anisotropy and remanence for hydrides of both x = 0.5 and 1.0 and these are found to be further enhanced at 24 K. These results are discussed on the basis of rhombohedral distortions of the crystal lattice. The magnetic moments of the hydrides are found to be less than those of the unhydrided materials.

Journal	Data powered by TypesetSolid State Communications
Publisher	Data powered by TypesetElsevier Ltd
ISSN	00381098
Open Access	No