摘要:

Temperature and magnetic field dependence of amorphous Fe‐B‐C alloys obtained by splat cooling were measured and compared with those of Fe‐B alloys. It was found that the effect of replacing boron by carbon in Fe86B14alloy was to change significantly the temperature dependence of magnetization in the direction of increasing spin‐wave stiffness, and to reduce the saturation susceptibility. The high value of room temperature saturation induction found in Fe‐B‐C alloy is therefore attributed to a change in the temperature dependence of magnetization, rather than to change in the magnetic moment at 0 K.

ISSN:0021-8979    

DOI:10.1063/1.327250

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We report systematic studies on the electrical resistivity, &rgr;, in the amorphous transition metal based alloy series T1−yGy, with T = A1−xBx(where A,B = Fe, Co, Ni, Cr, Mn) and the metalloid G (=P, B, Si, Al) over the temperature range 20 mK to 300 K. All the alloys studied show a minimum in the resistivity at a characteristic temperature Tminwhich varies from 8 K to 250 K depending on the system. For a given system the resistivity rise below tminis found to be a maximum around the critical conc region where the magnetic long‐range order parameter →0. Also, in all the alloys below the resistance minimum it is found that d&rgr; (T)/dT∼–&rgr; (T) with deviations setting in at lower temperatures. The coefficient of the T2term in &rgr; above Tminis strongly influenced by the metalloid concentration.

ISSN:0021-8979    

DOI:10.1063/1.327251

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The effects of processing conditions on the physical properties of Fe40Ni40B20amorphous alloys produced by a single roll‐casting technique were investigated. These results are discussed in terms of the cooling rate in the casting and the state of disordered structure quenched into the amorphous alloy.

ISSN:0021-8979    

DOI:10.1063/1.327252

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A method for measuring magnetic losses in amorphous alloys is described.It is based on the use of a lock‐in amplifier to determine the magnitude and phase of the fundamental component of magnetic field H when the induction B is forced to vary sinusoidally with time. The method is applicable to very small samples in the form of straight lengths or of toroids, and gives satisfactory results at flux levels approaching saturation if the flux wave form can be held sinusoidal. Data are presented on several amorphous alloy compositions as a function of peak induction and of frequency. Annealing effects have been investigated.

ISSN:0021-8979    

DOI:10.1063/1.327253

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Magnetic properties of reduced titanium phosphate glasses are reported. Magnetic susceptibility measurements from 1.0° to 400°K indicates behavior typical for amorphous antiferromagnetism. The more reduced glasses show an anomalous field dependence in the susceptibility suggestive of ferromagnetism. A microstructural model for the glasses is developed from physical, chemical and magnetic data. Using the model, a theoretical magnetic susceptibility equation is derived. The equation includes contributions to a total susceptibility from isolated Ti(3+) ions and ion pairs which participate in exchange. From electron spin resonance results, the theoretical susceptibility equation and the experimental Ti(3+) ion concentration in the glasses, a good fit to the experimental magnetic susceptibility data is obtained. Results from the theoretical equation indicates that ferromagnetic and antiferromagnetic interaction between exchange‐coupled Ti(3+) ions may occur. At low temperatures a downward curve toward the origin of the inverse susceptibility is predicted which is consistent with the experimental data.

ISSN:0021-8979    

DOI:10.1063/1.327254

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The annealing behavior of amorphous Co‐Fe‐B and Fe‐B thin films, fabricated by RF sputtering in an Ar plasma, has been investigated. (AIP)

ISSN:0021-8979    

DOI:10.1063/1.327263

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

This study of amorphous Gd‐Mn, Y‐Mn and their ternary alloys with Co prepared as films by co‐evaporation indicates that, (a) the Mn moment is compositionally dependent going from ?2&mgr;Bto 0.5&mgr;Bper Mn with increased Mn concentration in the alloy, (b) Gd‐Mn and Gd‐ (CoMn) order with antiparallel Gd and Mn moments or (CoMn) moments while Y‐Mn samples remain paramagnetic, (c) Curie temperatures are relatively constant with composition which we have interpreted in terms of the Mn‐Mn exchange interaction, and (d) the spontaneous Hall effect for Mn as given by &rgr;H/&rgr; (Hall resistivity/sample resistivity) is about −0.01 per &mgr;Bof Mn which is opposite in sign to Fe or Co.

ISSN:0021-8979    

DOI:10.1063/1.327264

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Results are reported on the magnetic properties of (R65Fe35)100−xBxglasses, where R denotes Y, Gd, and Er, and x is 10 or 20. Curie‐Weiss fits were made to high temperature susceptibility data to determine average effective moments per magnetic ion and Weiss temperatures. Hysteresis loops and modified Arrott plots were used to determine the spontaneous magnetizations, coercive forces, and ordering temperatures. The effective moments and spontaneous moments are compared with those calculated on the assumption of local moments on both magnetic subnetworks, and assuming various spin structures. There is evidence for moment instabilities on Fe atoms in the Y‐Fe‐B glass, depending on local‐environment effects. Local random anisotropy plays an important role in Er‐Fe‐B but not in Gd‐Fe‐B.

ISSN:0021-8979    

DOI:10.1063/1.327265

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A very large aftereffect is observed in sputtered amorphous Tb‐Fe films with uniaxial anisotropy perpendicular to the film plane. In the present experiment, the film is first saturated to −Msby a premagnetizing field Hp(<0), where Msis the saturation magnetization. Then the applied field is suddenly changed from Hp(<0) to Ha(?0) which is close to the coercive field. With proper choice of the film composition, temperature, Haand so on, the magnetization changes from −Msto almost +Mswith the passage of time while Hais kept constant. The dependences of the aftereffect on the applied field and on the temperature are shown. The domain observation by means of polar Kerr effect reveals that the aftereffect is associated with the slow dendritic growth of the magnetic domains. It is also found that the density of reversed domain nuclei depends on the premagnetizing field Hp.

ISSN:0021-8979    

DOI:10.1063/1.327266

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Spin resonance measurement on bulk samples of a‐YFe2, grown by d.c. sputtering, and a thin film of Y0.30Fe0.70, grown by co‐evaporation, are reported. In agreement with our earlier reports, we observed a multi‐line spectrum in which one line has a frequency and angular dependence expected from a thin ferromagnetic layer with (4&pgr;M)eff≳6 kOe at 300 K despite the fact that a‐YFe2is known to have no long range order at this temperature. Rutherford back‐scattering, chemical etching studies, and temperature dependence of (4&pgr;M)efflead us to conclude that the ferromagnetic layer is not a consequence of segregation, surface contamination or locally crystallized material. We propose that it arises from some kind of an atomic rearrangement which is initiated at the surface and progresses inward on a time scale of weeks.

ISSN:0021-8979    

DOI:10.1063/1.327267

出版商:AIP    

年代:1979

数据来源: AIP