共查询到20条相似文献,搜索用时 31 毫秒
1.
Widatallah H. M. Gismelseed A. M. Bouziane K. Berry F. J. Al Rawas A. D. Al-Omari I. A. Yousif A. A. Elzain M. E. 《Hyperfine Interactions》2004,158(1-4):223-227
Perturbed Angular Correlation method has been used to study the hyperfine magnetic field in the Heusler alloy Pd2MnSb(Sn). Ion implantation of the recoil 111In nuclei following heavy ion nuclear reactions 108Pd(7Li, 4n)111In and 108Pd(6Li, 3n)111In has been used to great advantage in the present case resulting in large implantation efficiency. Only a few hours of irradiation
time with moderate beam current of the order of 400–500 nA resulted in sufficient implanted 111In activity on the sample for good quality measurements. The hyperfine field was measured at 111Cd probe nuclei substituting Mn and Sb(Sn) sites as a function of temperature. The fraction of 111Cd nuclei occupying Mn atom sites was found to increases with the annealing of sample at higher temperatures. 相似文献
2.
The results of extensive magnetisation, X-ray and neutron powder diffraction measurements on the intermetallic compound series Ni2-xMnSb, for 0?x?1, are reported. For x ?0.4, a high degree in the C1b structure is observed, but for x?0.3, some disorder is evident. The series is ferromagnetic, with Curie temperatures rising from 368 to 732 K with decreasing nickel concentration. The magnetic moments all lie in the range (4.0±0.3)μB, with a maximum at a composition near x=0.45. The magnetic moments are largely associated with the ordered manganese sites, but it is possible that a small negative moment ?0.25μB may be associated with the “nickel sites” for x?0.3. This latter moment may be accounted for by disordered Mn atoms antiferromagnetically aligned. 相似文献
3.
Measurements of the hyperfine magnetic fields Bhf of Te and I impurities substituting Sb in the Heusler alloys Pd2MnSb and PdMnSb clearly establish that the curve of Bhf versus impurity atomic number is shifted to the right by about 1 unit of atomic number for PdMnSb relative to Pd2MnSb. This phenomenon, and the general shape of the curve can be understood in terms of the conduction electron polarization model developed by Blandin and Campbell. 相似文献
4.
The spin polarization of electrons tunneling from MnxSb1?x was measured over the full Mn concentration range 0 ? x ? 1. The polarization is positive and qualitatively similar to the magnetization per Mn atom of bulk material; for MnSb (x = 0.5) it is + 25%. 相似文献
5.
G. Crecelius H. Maletta H. Pink W. Zinn 《Journal of magnetism and magnetic materials》1977,5(2):150-155
We report on a Mössbauer study of the transferred hyperfine fields at the 151Eu nuclei in the Eu1?xSrx series of mixed compounds. The totally transferred hyperfine field amount ?(5.3 ± 0.3) T corresponding to saturation values for the hyperfine field of ?(33.4 ± 0.2) T for x = 0 and ?(28.1 ± 0.2) T extrapolated for x = 1. Our results strongly support fairly long range magnetic interactions instead of the generally accepted model covering only nearest and next nearest neighbour interactions. 相似文献
6.
Y. Ueda K. Kosuge S. Kachi H. Yasuoka H. Nishihara A. Heidemann 《Journal of Physics and Chemistry of Solids》1978,39(12):1281-1285
The local magnetic properties of the V sites in the nonstoichiometric V2O3+x (0 ? x <0.08) have been examined by nuclear magnetic resonance and inelastic spin-flip neutron scattering techniques. The samples with x = 0.01 and 0.02 show a paramagnetic metal (PM)-antiferromagnetic insulator (AFI) transition. In the AFI phase, two distinct 51V NMR signals with hyperfine fields Hn = 184.9±0.5 kOe and 71±1 kOe were observed at 1.8 K, which were assigned as due to V3+ and V3+ sites, respectively. On the other hand, the samples with x = 0.04 and 0.06 were metallic down to 1.4K, and showed a paramagnetic (PM)-antiferromagnetic (AFM) transition at about 10 K. In these samples, a 51V NMR signal with Hn = 58±2 k0e and one with 〈Hn〉 = 9kOe were observed at 1.8 K, which were assigned as due to V3+-like sites and the matrix V sites, respectively. These results are entirely consistent with those obtained from the neutron experiment. We propose that in the metallic phase (0.04 ? x < 0.08) the minority V4+-like sites are magnetically localized in the delocalized V matrix and may be responsible for the antiferromagnetic long range order below 10 K. 相似文献
7.
Zero-field 57Fe Mössbauer spectroscopy has been used to study the magnetic properties of an amorphous melt–spun Pd40Ni40?x Fe x P20 (x?=?5, 10, 17.5, 20) series. The alloys show quadrupole split doublets at room temperature indicating paramagnetic behaviour. At low temperatures the Mössbauer spectra are sextets due to the onset of long range order. The transition temperatures increase with Fe concentration from 12?±?2 K for Pd40Ni35Fe5P20 to 42.0?±?2.0 K for Pd40Ni20Fe20P20. The hyperfine field was found to follow $ {\text{Hf}}{\left( {\text{0}} \right)}{\left( {{\text{1 - }}T \mathord{\left/ {\vphantom {T {T_{{\text{c}}} }}} \right. \kern-0em} {T_{{\text{c}}} }} \right)}^{{\text{ $ \beta $ }}} $ over the critical region with the β exponent being close to 0.4. 相似文献
8.
M. Gogołwicz J. Warczewski T. Mydlarz I. Okońska-Kozłowska 《Journal of magnetism and magnetic materials》1985,50(1):49-52
For the polycrystalline samples of Mn1?xCuxCr2S4 (x = 0.85, 0.90, 0.95) the magnetization was measured in the temperature range between 77 K and the Curie temperature, TC, using a magnetic balance (Faraday's method) and pulsed magnetic fields up to 2.0 T. The magnetic susceptibility was measured between TC and about 600 K. The Curie temperatures were obtained using the kink point method.In the temperature range between 4.2 and 77 K the magnetization was measured in stationary magnetic fields up to 14 T. The data indicate a noncollinear ferrimagnetic structure. The compounds under investigation can be treated as CuCr2S4 slightly doped with Mn, with a valence distribution Mn2+1?xCu1+xCr3+2?xCr4+xS2?4. 相似文献
9.
The properties of ferromagnetic Gd as a host for IMPAC measurements have been investigated. The transient and internal magnetic fields at Cd, Nd, Sm, Dy, Er, Yb and Hf nuclei recoil implanted into polarized Gd at 80 K have been studied by the IMPAC technique. All available experimental transient field data for Gd have been analysed in the framework of the Lindhard-Winther theory. Empirical values of the parametersv p andC ion C atom have been deduced which give good agreement between experiments and theory. Internal magnetic fields at rare-earth nuclei in magnetized Gd at 80 K have been deduced. The results areH h.f. (NdGd)=?1370±440 kG,H h.f.(SmGd)=?1440±120 kG,H h.f.(DyGd)=1410±400 kG,H h.f.(ErGd)=2310±420 kG andH h.f.(YbGd)=?216±32 kG. The signs of these fields are, except for Yb which is in a 2+ ionic state, consistent with a ferromagnetic coupling between the 4f spins of the implanted ion and the Gd host. The deduced internal field at Hf in Gd is ?440±90 kG. The observed time-dependent interactions for rare-earth nuclei in ferromagnetic Gd are consistent with the Abragam-Pound theory. For the Cd isotopes,g-factors of the first 2+ states were deduced from the experiments. The results areg(110Cd)=0.49±0.11,g(114Cd)=0.34±0.09 andg(116Cd)=0.41±0.11. The use of transient magnetic fields forg-factor measurements on high-spin rotational states is discussed. 相似文献
10.
The magnetic hyperfine field at 121Sb in Pd2MnSb has the anomalously large value (at 100 K) of ±579 ±5 kG. In the closely related compound PdMnSb we find ±302 ±5 kG, similar to other ferromagnetic intermetallics containing Mn and Sb. 相似文献
11.
Magnetization, susceptibility, X-ray and neutron diffraction measurements have been made on the two series of alloys Pd2MnIn1?xSnx and Pd2MnSn1?xSbx, for 0 ? x ? 1. All were single phase and were chemically ordered intermetallic compounds with the Heusler L21 structure in which the Mn atoms occupy an f.c.c. sub-lattice. At all compositions the alloys were magnetically ordered with a moment of ~4.3 μB located at the Mn sites. At the In-rich end the magnetic order is antiferromagnetic f.c.c. type 2. As Sn is increasingly substituted for In there is a change in magnetic order first to antiferromagnetic f.c.c. type 3A and then to ferromagnetism. All the alloys in the Sn/Sb series are ferromagnetic and in both series there is an increase in the ferromagnetic exchange interactions with increasing electron concentration. 相似文献
12.
LIII absorption edges of cerium in ternary AuCu3 compounds Ce(Pd1?xMx)3 (M = Ag and Rh) and (Ce1?xYx)Pd3 are presented. We find that Ce in these compounds is mixed valent with nf ? 0.7. The valence V of Ce(Pd1?xRhx)3 becomes concentration independent of V = 3.29 ± 0.02 for x ? 0.18. In Ce1?xYxPd3 we observe the valence to increase up to V = 3.32 ± 0.02 at the highest concentration of Y. We show, that a critical volume, available for the Ce atom, is associated with the concentration independent valence around 3.3. For both systems, linewidths W1, W0 and Δ = E(4f1) ? E(4f0), as derived from LIII double-bump structure, are given. Possible falsifications due to “final states effects” on the valence are discussed. 相似文献
13.
By means of Christiansen filter technique the following bound coherent neutron scattering lengths were obtained:natRu:b=7.02 ± 0.02 fm108Cd:b=5.31 ± 0.24 fm103Rh:b=5.90 ± 0.04 fm110Cd:b=5.78 ± 0.08 fmnatTl:b=8.773 ± 0.015 fm111Cd:b=6.47 ± 0.08 fm203Tl:b=8.51 ± 0.08 fm112Cd:b=6.34 ± 0.06 fm205Tl:b=8.87 ± 0.07 fm114Cd:b=7.48 ± 0.05 fm116Cd:b=6.26 ± 0.09 fm In combination with some total cross section measurements with neutrons in the eV-energy range and with the compiled resonance parameters we deduced consistent sets of spin state scattering lengths and potential radii. 相似文献
14.
27Al and55Mn nuclear magnetic resonance shift,K, and27Al spin lattice relaxation time,T
1, have been measured for the six-dimensional face-centered icosahedral quasicrystals, Al75-x
Pd15Mn10+x
withx=0, 2 and7. The Al75Pd15Mn10 quasicrystal exhibits a temperature independent Knight shiftK and(T
1
T)–1=0.022±0.002 (K s)–1 in a temperature range from room temperature to 5 K because there exist no Mn atoms with local magnetic moment. The replacement of Al with Mn drastically decreases the27AlK, the55MnK andT
1 of27Al, andthe27AlK becomes negative. There is an additional contribution to the spin lattice relaxation time independent of temperature. This is considered to be due to the presence of a localized magnetic moment in the replaced Mn atoms. 相似文献
15.
Lidia Rednic Iosif G. Deac Eugen Dorolti Marin Coldea Vasile Rednic Manfred Neumann 《Central European Journal of Physics》2010,8(4):620-627
X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM) and magnetic measurements as a function of applied magnetic field and temperature for In1?x Mn x Sb (0.05≤x≤0.2) system are reported. Magnetic measurements performed at high and small magnetic field in ZFC and FC indicate the coexistence of ferromagnetic In1?x Mn x Sb solid solution and two types of magnetic cluster: ferromagnetic MnSb and ferrimagnetic Mn2Sb. XPS valence band and Mn 2p core level spectra have confirmed the presence of MnSb and Mn2Sb phases. TEM images show some manganese antimonide phase microinclusions with dimension between (30–40) nm. 相似文献
16.
W. Reimers E. Hellner W. Treutmann P.J. Brown 《Journal of Physics and Chemistry of Solids》1983,44(3):195-204
In order to study the influence of interstitial site occupancy on the electronic structure of MnSb, a polarised neutron diffraction experiment was performed on Mn1.09Sb. The composition of the sample was obtained from the refinement of single crystal neutron diffraction data. The polarised neutron diffraction experiment yielded unpaired electron populations of the levels at1g, egt and eg as follows: μx0 = 0.57 μB, μx± = 1.60 μB, μu± = 1.28μB. The comparison of these numbers with results of Yamaguchi et al shows that the spin density for this composition is reduced for the low energy level at1g. This finding is interpreted by an occupation of minority spin states by electrons of the interstitial Mn atoms. In agreement with this, increasing Mn excess leads to a decreasing magnetic moment magnitude/Mn-atom and to a contraction of the lattice parameter c, indicating the strengthening of the Mn-Mn bond in [001]. 相似文献
17.
Magnetism of MnSix, x=1.746 (Mn27Si47) was investigated by SANS, neutron diffraction, magnetization and magnetic susceptibility measurements. MnSix single crystalline specimens were characterized by X-ray and neutron diffraction. A spiral spin structure with periodicity ?=(163±4) Å along the c axis and a spiral component of the magnetic moment per Mn of po=0.056 was determined. From the field dependence of ? it is indicated that the magnetic order below TN=42 K is an incommensurate state. From the large difference of the magnetic moments in the paramagnetic state and ordered state MnSix is classified as an itinerant magnet. Below TN the difference of the magnetic moments per Mn between po=0.056 at H = 0 from SANS and ps = 0.014 at saturation field from magnetization measurements is explained by longitudinal spin fluctuations. 相似文献
18.
Magnetization and spin-flip Raman measurements are reported for Cd1?xMnxSe, x = 0.106, at 1.9 < T < 4.2 K and magnetic fields H up to 80 kOe. The high-field results are combined to determine the exchange energy between donor electrons and Mn++ spins, αN0=261±13 meV. Empirical fits to the magnetization data are described. 相似文献
19.
The TDPAC technique was used to measure the magnetic hyperfine field (mhf) acting on Cd impurity in the Heusler alloys Pd2MnIn1-xSnx and Pd2MnSn1-ySby for various values of x and y in the range 0 ? x, y ? 1. The alloys of Pd2MnIn1-xSnx are antiferromagnetic at the In-rich end and ferromagnetic at the Sn-rich end, with a transition region x ≈ 0.5?0.7 where both phases coexist; the alloys containing Sn/Sb are ferromagnetic for all values of y. The mhf on the Cd impurity in the antiferromagnetic, transition and ferromagnetic regions of Pd2MnIn1-xSnx are respectively zero, -150 and -200 kOe. For the Sn/Sb alloys the field changes from -200 at the Sn-rich end to -235 kOe at the Sb-rich end. The values of the field very closely follow the trend of the ferromagnetic Curie temperatures for the same alloys as a function of the s-p electron concentration. The observed large distribution of field intensities (~20%) and the lower values of the field in the region x = 0.5?0.6 are attributed mainly to the effect of antiferromagnetic domains. The results are compared with previous Mössbauer mhf measurements at the sites of Sn and Sb in the same alloys as well as with measurements in other Heusler alloys. 相似文献
20.
D.K. Hohnke 《Journal of Physics and Chemistry of Solids》1980,41(7):777-784
As x in Zr(In)O2?x is increased from 0.08 to 0.16 (9–19 mole per cent In2O3) the activation energy E(x) for ionic conduction increases from 1.05 to 1.51 eV; the concuctivity decreases from 2 × 10?5 to 3 × 10?6Ω?1cm?1at 400°C, is composition-independent at about 580°C, and increases from 1 × 10?2 to 4 × 10?2Ω?1cm?1 at 800°C. The pre-exponential term of the Boltzmann-type conductivity equation depends exponentially on E(x), a much stronger dependence on x than theoretically expected with a model for ionic conductivity that includes nearest-neighbor defect interactions. Analysis of reported conductivity data for Zr(M)O2?x (M = Sc, Y, Ca and rare earth metals) and other doped oxide electrolytes with fluorite-type structure reveals that the same relationship is observed with these materials when x γ0.08. It is shown that ionic conduction in these oxides is consistent with nearest neighbor vacancy-cation defect interaction forx < 0.08 but that an additional complex interaction with composition-dependent free energy ΔG(x) occurs when xγ 0.08.The lattice constant of Zr(In)O2?x with the cubic fluorite-type structure is independent of composition, 5.114 ± 0.002 Å, in agreement with ionic size considerations. 相似文献