K. Hoshi

Mössbauer and neutron diffraction studies of BCC CrFeMn ternary alloys

Abstract Successive magnetic phase transitions of disordered BCC Cr65Fe20Mn15 alloy have been studied by Mossbauer effect and neutron diffraction measurements. The (1 0 0) antiferromagnetic peak was observed below TN by neutron diffraction, and it still exists at the temperature of the ferromagnetic phase, indicating that the antiferromagnetic phase should coexist with the ferromagnetism. The mean hyperfine field by Mossbauer effect begins to grow below TN with decreasing temperature and increases rapidly below TC and Tg. The hyperfine field distribution at 13 K shows two distinct peaks in an agreement with Cr80Fe20 alloy.

Magnetic properties of Ce(Ru1−xPdx)2Si2

Abstract The experimental results of the magnetic susceptibility, magnetization and specific heat measurements are presented for single crystalline samples of Ce(Ru1−xPdx)2Si2. We obtained a magnetic phase diagram of this system similar to the Ce(Ru1−xRhx)2Si2 systems. At low Pd concentration (0.03

Magnetic properties and phase diagram of amorphous Hf1−xTaxFe2, compounds*

We have measured the magnetization and Mossbauer effect on amorphous Hf 1− x Ta x Fe 2 alloys prepared by sputtering from 4.2 to 300 K. The alloys are found to be an itinerant electron ferromagnet with a wide distribution of the local Fe moment. The ferromagnetic moment decreases with increasing Ta concentration and becomes almost zero for x =1.

Resistivity of Ce(Ru0.85Rh0.15)2Si2 under pressure

Abstract Resistivity measurement on single-crystalline Ce(Ru0.85Rh0.15)2Si2 sample which shows a spin-density-wave (SDW) transition at a Neel temperature T N =5.5 K has been performed under hydrostatic pressure. A hump-type jump in resistivity due to the SDW transition shifts to lower temperature with increasing pressure, and finally disappears above P=0.5 GPa . The ratio of gapped part of the Fermi-surface along the c-axis is estimated as ∼0.45 for P=0 GPa and almost pressure independent.

Magnetic properties of concentrated melt-spun Fe–Y amorphous alloys

Abstract Phase diagram on melt-spun Fe x Y 100− x amorphous alloys was investigated through measurements of d M /d H , zero-field-cooled and field-cooled magnetization and EXAFS. The present result shows reentrant spin glass for 42⩽ x ⩽58 and spin glass for x ⩽40, which is different from previous studies for sputtered and other melt-spun samples. The magnetic phase change at x =40 can be attributed to the change of Fe–Fe distance or some other structural changes.

Mechanical milling of Fe72Pt28 alloy

Abstract Mechanical milling of ordered and disordered Fe 72 Pt 28 alloys was performed by vibrating milling. A martensitic transformation is induced in both alloys by milling, and the fundamental crystal structure re-transforms from bcc to fcc with heating up to 750 K. We can obtain fcc Fe 72 Pt 28 with different degrees of structural disorder by mechanical milling and subsequent heating of disordered Fe 72 Pt 28 . The Curie temperature of fcc Fe 72 Pt 28 with different degrees of structural disorder increases with increasing structural disorder.

Neutron diffraction and Mössbauer measurements for magnetism of BCC Cr-Fe-Mn alloys

Abstract The successive magnetic transition of BCC Cr 65.0 Fe 20.0 Mn 15.0 alloy has been studied by neutron diffraction and Mossbauer effect measurements. An antiferromagnetic 1 0 0 scattering and the hyperfine field at Fe sites were confirmed to appear just below T N by neutron diffraction and Mossbauer effect, respectively. The hyperfine field distribution estimated from the Mossbauer spectra has two peaks below 150 K. The amount of Fe atoms for the peak of the high-field part increases with decreasing temperature at around T c . The position of the high-field peak shifts remarkably to higher field below T g with almost keeping the fractional area for this peak.

Muon spin relaxation studies in single crystals YRu2Si2 and Ce(Ru1−xRhx)2Si2

We have performed zero-field μSR measurements on high-quality single-crystalline samples of YRu 2 Si 2 , CeRu 2 Si 2 and Ce(Ru 0.85 Rh 0.15 ) 2 Si 2 from 2 K to 300 K. We got information on the diffusion and stopping site of muons in the ThCr 2 Si 2 structure from measurements on the non-magnetic reference compound YRu 2 Si 2 . The development of magnetic correlation of the Ce 4f moment was observed below 100 K on CeRu 2 Si 2 . Furthermore, the property of the antiferromagnetic ordering state of Ce(Ru 0.85 Rh 0.15 ) 2 Si 2 is discussed

μSR study of the heavy-electron system Ce(Ru1−xRhx)2Si2

Abstract We have performed zero- and longitudinal-field μSR measurements on polycrystalline Ce(Ru 1− x Rh x ) 2 Si 2 for x = 0 and 0.15 from 4 to 300 K. The development of a magnetic correlation has been found to start as high as room temperature for both systems with a quasistatic character. Another static inhomogeneous field partly occurs at 5.5 K for x = 0.15, suggesting a complicated antiferromagnetic ordering.

Magnetic and Mössbauer Study of Sputtered Amorphous Alloys Hf1-xTaxFe2

We have measured the magnetization and Mossbauer effect on vapor-quenched amorphous Hf 1- x Ta x Fe 2 alloys prepared by sputtering for x =0, 0.3, 0.5, 0.7, 0.9 and 1 from 4.2 to 300 K. We observed the spontaneous magnetization for all the present samples except for x =1, where the ferromagnetic moment and Curie temperature monotonically decrease with increasing Ta concentration. A comparison between the ferromagnetic and paramagnetic moments suggests that the alloys are an itinerant-electron ferromagnet. The reduced low-temperature magnetization falls characteristically below that of crystalline HfFe 2 and follows a T 3/2 law. From the broad Mossbauer spectrum below the Curie temperature we estimate the average hyperfine field. Ta-concentration and temperature dependence of the average hyperfine field agrees with that of the magnetization.