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Mesoscopic Magnetic States in Metallic Alloys with Strong Electronic Correlations: A Percolative Scenario for CeNi$_{1-x}$Cu$_{x}$

N. Marcano·J. C. Gomez Sal·J. I. Espeso·J. M. De Teresa·P. A. Algarabel·C. Paulsen·J. R. Iglesias
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Abstract

We present evidence for the existence of magnetic clusters of approximately 20 Åin the strongly correlated alloy system CeNi$_{1-x}$Cu$_{x}$ (0.7 $\le$ x $\le$ 0.2) based on small angle neutron scattering experiments as well as the occurrence of staircase-like hysteresis cycles during very low temperature (100 mK) magnetization measurements. An unusual feature is the observation of long-range ferromagnetic order below the cluster-glass transition without any indication of a sharp transition at a Curie temperature. These observations strongly support a phenomenological model where a percolative process connects the cluster-glass state observed at high temperatures with the long-range ferromagnetic order observed by neutron diffraction experiments at very low temperatures. The model can account for all the puzzling macroscopic and microscopic data previously obtained in this system, providing a new perspective with regard to the magnetic ground state of other alloyed compounds with small magnetic moments or weak ferromagnetism with intrinsic disorder effects.

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N. Marcano, J. C. Gomez Sal, J. I. Espeso, J. M. De Teresa, P. A. Algarabel, C. Paulsen, J. R. Iglesias. 2007-03-15. Mesoscopic Magnetic States in Metallic Alloys with Strong Electronic Correlations: A Percolative Scenario for CeNi$_{1-x}$Cu$_{x}$. https://arxiv.org/abs/cond-mat/0703399

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