摘要:

The A2→DO3,B2,B32 disorder‐order transformation in Fe2.7Mn0.3Si is studied using Mo¨ssbauer spectroscopy. The ‘‘kinetic path’’ for ordering shows development of B32 and DO3type ordered phases in this alloy.

ISSN:0094-243X    

DOI:10.1063/1.44698

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A combined ac susceptibility, ferromagnetic resonance, and Mo¨ssbauer effect study on the concentrated spin system Fe2MnSi with mixed exchange interactions shows that it goes to a ferromagnetic state atTC=237 K followed by a transition to a reentrant state atTRE=60 K. The magnetic state of the system can be consistently described in terms of a ferromagnetic matrix plus finite spin clusters model.

ISSN:0094-243X    

DOI:10.1063/1.44699

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A detailed ‘‘zero‐field’’ Mo¨ssbauer and ferromagnetic resonance (FMR) study of a‐Fe90−xCoxZr10alloys with 0≤x≤10 reveals that (i) alloys withx≤2 exhibit at low temperatures properties that are reminiscent of reentrant spin glass behavior (ii) for such alloys, the hyperfine field distributionP(H) isbimodaland comprises two Gaussian distributions and the peak‐to‐peak FMR linewidth, &Dgr;Hpp, diverges exponentially forT<TC(iii) forx≥4, the low‐field Gaussian component inP(H) and the divergence in &Dgr;Hppat low temperatures both get completely suppressed. These observations imply that the reentrant behavior gets progressively suppressed with partial replacement of Fe with Co. All the diverse aspects of the present results have been interpreted in terms of the ferromagnetic matrix plus finite spin clusters model.

ISSN:0094-243X    

DOI:10.1063/1.44700

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The magnetic behavior of a disordered binary alloyAxB1−x, whereAandBare respectively ferromagnetic and paramagnetic metals, is studied based on periodic Anderson model and using HF and virtual crystal approximation. The effect of alloying is incorporated by changing the total number of electrons. Re‐entrant magnetic behavior is observed within a limited range of parameters of the model.

ISSN:0094-243X    

DOI:10.1063/1.44701

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Angular dependence of ferromagnetic resonance fields in amorphous Fe90−xCoxZr10alloys with 0≤x≤10 has been measured for both in‐plane and out‐of‐plane sample geometries. This angular variation has been fitted to theoretical resonance expressions which take into account the uniaxial anisotropy. The uniaxial anisotropy field,Hk=2Ku/Ms, increases with Co concentration and scales with saturation magnetization,Ms.

ISSN:0094-243X    

DOI:10.1063/1.44702

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Contrary to earlier reports, a detailed ferromagnetic resonance (FMR) study in the critical region of Fe90−xCoxZr10alloys with 0≤x≤10 shows that the critical exponents &bgr; and &ggr; for spontaneous magnetization and initial susceptibility, respectively, which characterize the ferromagnetic (FM)‐paramagnetic (PM) phase transition at the Curie temperature,TC, possess values which are close to the three‐dimensional Heisenberg values and areindependentofcomposition. The fraction of spins that participates in the FM‐PM phase transition possesses a value of 11% for the alloy withx=0 and increases with Co concentrationx. The peak‐to‐peak FMR linewidth is governed by the Landau‐Lifshitz‐Gilbert relaxation mechanism in the critical region and the Lande´ splitting factorgand the Gilbert damping parameter &lgr; areindependentof temperature. While &lgr; decreases withx,ghas a constant value of 2.07±0.02.

ISSN:0094-243X    

DOI:10.1063/1.44703

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A detailed analysis of the results of high‐precision bulk magnetization and ac susceptibility data taken in the critical region on amorphous Fe16Ni64B19Si1alloy before and after it had undergone isothermal annealing treatment atTA=400 K for durations of timetA=60 and 120 minutes reported in this paper reveals that the structural relaxation consequent upon isothermal annealing does not affect the asymptotic and ‘‘correction‐to‐scaling’’ (CTS) critical exponents but has marked influence on the CTS amplitudes.

ISSN:0094-243X    

DOI:10.1063/1.44705

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Asymptotic values of the critical exponents &bgr; and &ggr; and amplitudesm0,m0/h0for spontaneous magnetization,M27and initial susceptibility, &khgr;0, are determined by the ‘‘range‐of‐fit’’ scaling‐equation‐of‐state (SES) analysis of the magnetization data, deduced from the ferromagnetic resonance (FMR) spectra taken in the temperature range −0.15≤&egr;=T−TC/TC≤0.15 (TC=Curie temperature) on amorphous (a−) Fe83−XWXB17alloys withX=5 and 9. The exponent values are same as those predicted for three‐dimensional Heisenberg spin system with nearest neighbor interactions. The Gilbert damping parameter &lgr; is temperature‐independent and increases with increasingWconcentration.

ISSN:0094-243X    

DOI:10.1063/1.44706

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Bulk magnetization data taken on amorphous Fe16Ni64B19Si1and Fe20Ni60B20alloys in the temperature range 0.9  TC≤T≤1.4  TCreveal that the magnetization data satisfy the generalized equation of state, which takes into account the relevant and irrelevant scaling fields and is based on the nonlinear variables &egr;˜=(T−TC)/T=&egr;/tandh˜=H/t(wheret=T/TC), whereas the initial susceptibility data obey the modified Curie‐Weiss law in the entire temperature range. Moreover, the present results provide a strong evidence for weak itinerant ferromagnetism in the alloys in question.

ISSN:0094-243X    

DOI:10.1063/1.44707

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

High precision four terminal dc electrical resistivity (&rgr;) measurements are carried out on amorphous Fe75−xMxSi15B10(M= Co, Cr; 0 ≤x≤ 9)alloys in the temperature ranges 1.5≤T≤300 K and 77≤T≤400 K for Co and Cr substituted samples, respectively. For both kind of samples studied, the temperature dependence of resistivity shows a minimum (&rgr;min) at a temperatureTmin×Tminvalue for amorphous Fe75Si15B10alloy is 20 K and it does not get affected with Co substitution whereas it increases drastically to high temperatures with the same amount of Cr substitution. &rgr; shows a logarithmic temperature dependence for temperatures less thanTmin. AboveTmin , &rgr; shows quadratic temperature dependence. An indirect evidence for the magnetic contribution to total resistivity is presented by an elaborate resistivity data analysis.

ISSN:0094-243X    

DOI:10.1063/1.44708

出版商:AIP    

年代:1992

数据来源: AIP