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29-Si NMR and Hidden Order in URu2Si2

O. O. Bernal·C. Rodrigues·A. Martinez·H. G. Lukefahr·D. E. MacLaughlin·A. A. Menovsky·J. A. Mydosh
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Abstract

We present new 29-Si NMR spectra in URu2Si2 for varying temperature T, and external field H. On lowering T, the systematics of the low-field lineshape and width reveal an extra component (lambda) to the linewidth below T_N ~ 17 K not observed previously. We find that lambda is magnetic-field independent and dominates the low-field lineshape for all orientations of H with respect to the tetragonal c axis. The behavior of lambda indicates a direct relationship between the 29-Si spin and the transition at T_N, but it is inconsistent with a coupling of the nuclei to static antiferromagnetic order/disorder of the U-spin magnetization. This leads us to conjecture that lambda is due to a coupling of 29-Si to the system's hidden-order parameter. A possible coupling mechanism involving charge degrees of freedom and indirect nuclear spin/spin interactions is proposed. We also propose further experiments to test for the existence of this coupling mechanism.

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O. O. Bernal, C. Rodrigues, A. Martinez, H. G. Lukefahr, D. E. MacLaughlin, A. A. Menovsky, J. A. Mydosh. 2001-06-22. 29-Si NMR and Hidden Order in URu2Si2. https://doi.org/10.1103/physrevlett.87.196402

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