| Autor: |
Majumder, Mayukh, Ghoshray, Kajal, Ghoshray, Amitabha, Pal, Anand, Awana, Veer P. S. |
| Zdroj: |
Journal of the Physical Society of Japan; May 2012, Vol. 81 Issue: 5 p054702-054708, 7p |
| Abstrakt: |
31P NMR spectral features in polycrystalline SmCoPO reveal an axially symmetric local magnetic field. At low temperature, the anisotropy of the internal magnetic field increases rapidly, with $K_{ab}$ increasing faster than that of $K_{c}$. The dominant contribution to this anisotropy arises from Sm-$4f$ electron contribution over that of Co-$3d$. The intrinsic width $2\beta$ deviates from linearity with respect to bulk susceptibility below 170 K due to the enhancement of $(1/T_{2})_{\text{dynamic}}$, which along with the continuous increase of anisotropy in the internal magnetic field is responsible for the wipe out effect of the NMR signal, well above $T_{\text{C}}$. $1/T_{1}$ shows large anisotropy confirming a significant contribution of Sm-$4f$ electron spin fluctuations to $1/T_{1}$, arising from indirect RKKY type exchange interaction indicating a non-negligible hybridization between Sm-$4f$ orbitals and the conduction band, over the itinerant character of the Co-$3d$ spins. This anisotropy originates from the orientation dependence of $\chi^{\prime\prime}(\mathbf{q},\omega)$. The $3d$-spin fluctuations in the $ab$-plane is 2D FM in nature, while along the $c$-axis, a signature of a weak AFM spin fluctuations superimposed on weak FM spin-fluctuations even in a field of 7 T and far above $T_{\text{N}}$ is observed. The enhancement of this AFM fluctuations of the Co-$3d$ spins along $c$-axis, at further low temperature is responsible to drive the system to an AFM ordered state. |
| Databáze: |
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