The magnetic hyperfine field in the 181Ta site in the Co2HfAl and Co2HfGa Heusler alloys
Description
The hyperfine magnetic fields at 181Ta nuclei in Heusler alloys Co2HfZ (Z=Al, Ga) have been measured using the time differential perturbed gamma-gamma angular correlation (TDPAC) method. The hyperfine fields obtained from these measurements at the liquid nitrogen temperature are -189 and +- 150 kOersted for Co2HfAl and Co2HfGa, respectively. The concept that the hyperfine field at the Y site is similar to the solute fields in Fe, Co, Ni and Gd matrices is corroborated. We have verified that ratios H sub(hf) sub(Ta)/T sub(c) and H sub(hf) sub(Ta)μ sub(Co) in Co2HfZ compounds (Z=Al, Ga, Sn) do not depend on the nature of Z element. However a dependence in the value of observed field with the s-p element in Z site was noticed. We feel that the samples are not completely ordered cubic as observed by the quadrupole interaction measurements. The results are interpreted in terms of the Campbell-Blandin formalism, and it is shown that the spin polarization of conduction electrons at Hf and Ta have opposite signs. (Author)
Availability note (English)
MF available from INIS under the Report Number.Abstract (Portuguese)
Os campos hiperfinos magneticos sobre os nucleos de 181Ta nas ligas de Heusler Co2HfZ (Z=Al, e Ga) foram medidos por metodos de correlacao angular gama-gama perturbada diferencial. Os experimentos com as amostras a temperatura de nitrogenio liquido constataram campos de -189 e +- 150kOersted nos compostos Co2HfAl e Co2HfGa, respectivamente. Estes numeros confirman o conceito de que o campo na posicao Y nas ligas de Heusler, e aproximadamente igual ao obtido sobre o elemento como impureza em matrizes de Fe, Co, Ni e Gd. Notamos que as razoes CHM sub(Ta)/T sub(c) e CHM sub(Ta)/μ sub(Co) nos compostos Co2HfZ (Z=Al, Ga, Sn) independem da natureza do elemento Z. Todavia, verificamos que o valor do campo depende do particular elemento s-p no sitio Z. Pela presenca de interacoes quadrupolares, evidenciam-se defeitos na estrutura cristalina das amostras estudadas. A interpretacao dos resultados experimentais pelo modelo de Campbell-Blandin sugere que a polarizacao de spin dos eletrons de conducao sobre o Hf tem sinal oposto a existente no Ta. (Autor)Files
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Additional details
Additional titles
- Original title (Portuguese)
- O campo hiperfino magnetico no sitio do
Publishing Information
- Imprint Pagination
- 67 p.
- Journal Issue
- no. 149
- Series
- IEA Dissertacao e Tese.
- Report number
- IEA-DT--149
INIS
- Country of Publication
- Brazil
- Country of Input or Organization
- Brazil
- INIS RN
- 12572050
- Subject category
- S75: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY;
- Resource subtype / Literary indicator
- Numerical Data, Thesis
- Descriptors DEI
- DIFFERENTIAL PAC; ENERGY SPECTRA; EXPERIMENTAL DATA; HEUSLER ALLOYS; HYPERFINE STRUCTURE; MAGNETIC FIELDS; SPIN ORIENTATION; TANTALUM 181; TIME DEPENDENCE; ULTRALOW TEMPERATURE
- Descriptors DEC
- ALLOYS; ALUMINIUM ALLOYS; ANGULAR CORRELATION; COPPER ALLOYS; COPPER BASE ALLOYS; CORRELATIONS; DATA; HEAVY NUCLEI; INFORMATION; ISOTOPES; MANGANESE ALLOYS; NUCLEI; NUMERICAL DATA; ODD-EVEN NUCLEI; ORIENTATION; PERTURBED ANGULAR CORRELATION; SPECTRA; STABLE ISOTOPES; TANTALUM ISOTOPES; TRANSITION ELEMENT ALLOYS