Study of combined magnetic and electric hyperfine interactions for cadmium in Dysprosium by time differential perturbed angular correlations

Abstract

The combined magnetic and electric hyperfine interaction at the site of a 111Cd impurity in magnetically ordered Dysprosium has been investigated as a function of temperature by time differential perturbed angular correlation measurements. Three different phases have been found in metallic Dy with transition temperatures of 85 and 179 ~ in agreement with the results of bulk material measurements. In the paramagnetic phase above 179 ~ a pure electric quadrupole interaction has been observed. The various contributions to the electric fieldgradient are analyzed and it is shown, that the dominant contribution comes from the conduction electrons.In the ferromagnetic phase which extends from 0 to 85 ~ the magnetic byperfine field at the site of mCd has the same temperature dependence as the spontaneous magnetization. The value of the hyperfine field at 4.2 ~ is [Heffl =(221 _+ 4)kG. At 85 ~ a transition to the antiferromagnetic phase of Dy occurs, which shows a hysteresis of the transition temperature. In the antiferromagnetic phase the temperature dependence of the hyperfine field deviates considerably from the magnetization curve. It is suggested that this deviation might be due to a temperature dependence of the s--f exchange interaction.

Exchange Interaction and Hyperfine Fields at Nonmagnetic Impurities in Rare‐Earth Metals

“…h(Z')/m(Z')] for hf fields a t llaSn in I n the Dy matrix, in the region of the transition from ferromagnetism to antiferromagnetism, a jump of the hf field due to Sn is observed a t T,. A similar jump was observed for lWd [24]. At the same time, the behavior of magnetization, i.e.…”

“…8 one may conclude that the helical structure in the matrices of Dy and Ho gives rise to an additional reduction in the conduction-electron polarization in comparison with the polarization in a matrix with collinear ordering of moments, as in the case of Tb. The temperature dependences of hf fields a t lllCd in Dy and Ho [24,25] do not coincide with the matrix magnetization curve either, but in this case the values of deviation differ from those observed for the impurity Sn. h(Z')/m(Z')] for hf fields a t llaSn in I n the Dy matrix, in the region of the transition from ferromagnetism to antiferromagnetism, a jump of the hf field due to Sn is observed a t T,.…”

The magnetic hyperfine field at Cd nuclei in the rare earth ferromagnets Gd, Tb, Dy, Ho, Er and Tm

“…But for reasons discussed in detail in Ref. [20] it was assumed that only the magnetic hyperfine field shows a finite distribution. A Gaussian distribution was used in the analysis.…”

The Temperature Dependence of the Magnetic Hyperfine Field at 111Cd in Magnetically Ordered Holmium

“…The radioactive -3 impurity concentration was less than 10 at%. A four detector TDPAC apparatus can be found in (5,6). A satisfactory fit to the time spectra the diamagnetic impurity is taken into account,…”