摘要:

The temperature dependence of the Landau–Lifshitz damping parameter for pure iron has been obtained over the temperature range 290–800 K from the observed amplitude of 73‐GHz microwave radiation transmitted through thin single‐crystalline slabs, approximately 45 &mgr;m thick, at an applied magnetic field corresponding to ferromagnetic antiresonance (FMAR). FMAR occurs when the internal flux densityBsatisfies the conditionB=&ohgr;/&ggr;, where &ohgr; is the circular frequency of the microwave radiation and &ggr; is the gyromagnetic ratio. An applied magnetic field parallel with the specimen plane was used. The Landau–Lifshitz damping parameter was found to increase slowly and monotonically with temperature from the room‐temperature value (0.70 ± 0.06) × 108Hz to (0.86 ± 0.06)× 108Hz at 800 K.

ISSN:0021-8979    

DOI:10.1063/1.349902

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The resistivity, ac susceptibility, and thermal expansion of single‐crystal Dy have been measured at temperatures below 10 K. Single‐crystal Dy is known to have a ferromagnetic structure with the magnetic moments confined to the basal plane at temperatures belowTc=90 K. At temperatures betweenTc=90 K andTN=180 K, single‐crystal Dy has a spiral antiferromagnetic arrangement of the magnetic moments with the screw axis along thecaxis. The existence of an additional anomaly nearT=6 K in ac susceptibility measurements of a very pure single crystal of Dy has been reported previously. Further evidence for a low‐temperature transition (T<6 K) in single‐crystal Dy is reported. The earlier ac susceptibility anomaly has been reproduced using a second, independently prepared crystal. Thermal‐expansion data show a second‐order phase transition near 5.9 K. A step has been observed intermittently in the resistivity along theaandcaxes at 6.5 and 6 K, respectively.

ISSN:0021-8979    

DOI:10.1063/1.349903

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The results of magnetic measurements performed on ZrCo5.1−xFexalloys in the temperature range 4.2–900 K and fields up to 7 T are reported. The presence of solid solutions is evidenced in the composition rangex<0.9. The Curie temperature and the saturation magnetization increase nearly linearly when cobalt is substituted by iron. In addition, the anisotropy field decreases and shows an unusual temperature dependence, with a maximum atT&bartil;300 K.

ISSN:0021-8979    

DOI:10.1063/1.349904

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The lattice parameters and the saturation magnetization are measured for the series of intermetallic compoundsA(Fe,B)2,A=Zr, Hf andB=Si and Al, with concentrations less than 15%. The magnetization measurements and the lattice parameter behavior are qualitatively discussed.

ISSN:0021-8979    

DOI:10.1063/1.349907

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The magnetic and structural properties of Co100−xMnxalloys have been studied in the range 0≤x≤50 at. %. The structural phase diagram, which was revised with the aid of resistivity and thermal‐expansion measurements for 4<T<1200 K, shows that the fcc↔hcp (&ggr;↔&egr;) martensitic transformation temperature in Co‐rich ferromagnetic CoMn alloys decreases progressively with increasing Mn content and vanishes atx&bartil;32 at. %, rather than abruptly decreasing at a lower concentration as previously suggested. It is found that antiferromagnetic order, which occurs atx≳32 at. %, causes a large increase in the atomic volume, thereby preventing the structure from collapsing into the smaller volume hcp phase. The atomic volumes at 0 K of fcc Co and fcc Mn, which were determined by extrapolation, were found to be in good agreement with those obtained from band calculations.

ISSN:0021-8979    

DOI:10.1063/1.349881

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Fe‐Cr‐Mn alloys with 10 at. % Mn have similar structural and magnetic properties as Fe‐Cr alloys, but have considerably higher Ne´el temperatures for the same Fe/(Fe+Cr) content ratio. When segregated, the high Ne´el temperatures of Fe‐Cr‐Mn alloys make it possible to investigate the magnetic nature of the Cr‐ and Fe‐rich components. Resistivity and magnetization measurements show distinct features that correspond to a superposition of the properties of the individual segregated components.

ISSN:0021-8979    

DOI:10.1063/1.349882

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The electronic states of a range of Fe‐Si alloys were investigated by x‐ray and ultraviolet photoelectron spectroscopy. Previous work has shown that in Fe‐Si alloys, the 6.5‐wt % Si‐Fe alloy has the optimum soft magnetic properties because of its zero magnetostriction. The binding energy (BE) of the Fe 2p, Fe 3s, Fe 3p, and Si 2plevels and the Fe 3dvalence‐band structures of Fe‐Si alloys were measured over the range from 0 to 7 wt % Si. The BE of the Fe 3sand Fe 3plevels and the Fe 3dvalence band of Fe‐Si alloys showed small shifts of the peaks toward higher BEs than pure Fe. These peak shifts are related to the change in density of Fe 3dstates with the addition of Si: the decrease in the density of states near the Fermi energy, the decrease in the energy difference between the majority and minority spin bands, and the increase in the number of electrons with minority spin. The results of the photoelectron spectroscopic analyses agree with the observed decrease in saturation magnetization from 2.15 T for pure Fe to 1.80 T for 6.5‐wt % Si‐Fe.

ISSN:0021-8979    

DOI:10.1063/1.349883

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

By growing gadolinium films on W(110), it has been possible to observe the development of the Gd(0001) band structure with increasing film thickness. The changes in the 5dbands as a result of exposure to oxygen or the development of the valence‐band structure with increasing film thickness lead to changes in the 5pmultiplet oscillator strengths. These changes are a result of the influence of the band structure upon the final‐state effects that give rise to such multiplet structures. This study provides conclusive evidence that there is a 5dcontribution to the shallow 5pmultiplet photoemission core‐level structure.

ISSN:0021-8979    

DOI:10.1063/1.349858

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A scheme, based on the linear muffin‐tin orbital (LMTO) formalism in the atomic sphere approximation (ASA) and on the recursion method, has been developed which allows first‐principles, spin‐polarized, self‐consistent, density‐functional calculations to be performed in real space. The scheme has been tested with success in ferromagnetic FeNi3and in antiferromagnetic FeMn. Here a substitutional impurity of Fe in a Cu host is considered. The first‐principles LMTO‐ASA real‐space approach is used to obtain the electronic structure and local magnetic moments of atoms in a region including four shells of Cu atoms around the impurity. The results for the magnetic moment and local density of states at the Fe site agree well withabinitioKKR–Green’s‐function results in the literature. The first‐principles real‐space approach is extremely flexible and can be applied to investigate interactions between impurities in a nonmagnetic host or between magnetic layers separated by nonmagnetic regions. It can also handle, without extra effort, lattice relaxation around the impurities.

ISSN:0021-8979    

DOI:10.1063/1.349859

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

In this work a quantum‐theoretical calculation of ferromagnetic domain walls in 3dtransition metals is presented. The model is based on a tight‐binding description of the system and the 3delectronic structure is obtained self‐consistently by use of the real‐space recursion method. A salient feature of this model is that both the orientation and the magnitude of the atomic magnetic moments are free to vary. This is in sharp contrast with classical studies which are based on theaprioriassumption that the magnitude of the moment is constant. Preliminary numerical results for a ferromagnetic chain are given.

ISSN:0021-8979    

DOI:10.1063/1.349860

出版商:AIP    

年代:1991

数据来源: AIP