Markayendeyulu G

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.

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.

The magnetic properties of ball-milled TbFe2 and TbFe2B were studied by magnetization measurements. X-ray diffraction studies on TbFe2B showed that boron occupied interstitial position in the crystal structure, just as hydrogen did. The value of the saturation magnetization of TbFe2B was found to be smaller than that of TbFe2. This is explained on the basis of a charge transfer between the boron atoms and the 3d band of Fe. The anisotropy of TbFe2B was found to be large compared to that of TbFe2. X-ray diffractograms for the ball milled samples showed that after 80 h of milling, a predominantly amorphous phase was obtained. TbFe2B was found to undergo easy amorphization compared to TbFe2. Magnetization of TbFe2 was found to decrease rapidly with initial milling hours and was found to be constant with further hours of milling. TbFe2B exhibited an anomalous behaviour with an increase in moment with milling hours and this may be due to the segregation of α-Fe.

Magnetic and electrical transport studies have been carried out on Ho 0.85Tb0.15Fe2-[x = 0-2] in the temperature range 5-300 K. The saturation magnetization at 5 K is found to increase with increasing Mn content due to the absence of Mn moments. The temperature variation of magnetization reveals several spin reorientation transitions and these are compared with the ac susceptibility results. Electrical resisitvity reveals the dominance of electron magnon scattering at low temperatures and electron-phonon scattering at high temperatures. © 2006 IEEE.

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.