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Weak magnetism phenomena in heavy-fermion superconductors: selected $μ$SR studies

A. Amato·M. J. Graf·A. de Visser·H. Amitsuka·D. Andreica·A. Schenck
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Abstract

The behavior of the so-called weak moment antiferromagnetic states, observed in the heavy-fermion superconductors UPt$_3$ and URu$_2$Si$_2$, is discussed in view of recent $μ$SR results obtained as function of control parameters like chemical substitution and external pressure. In UPt$_3$, the Pd substitution for Pt reveals the dynamical character of the weak moment order. On the other hand, $μ$SR measurements performed on samples in which Th substitutes U suggest that crystallographic disorder on the magnetic sites deeply affects the fluctuation timescale. In URu$_2$Si$_2$, a phase separation between the so-called hidden order state, present at ambient pressure, and an antiferromagnetic state, occurring under pressure, is observed. In view of the pressure-temperature phase diagram obtained by $μ$SR, it is deduced that the respective order parameters have different symmetries.

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A. Amato, M. J. Graf, A. de Visser, H. Amitsuka, D. Andreica, A. Schenck. 2004-08-16. Weak magnetism phenomena in heavy-fermion superconductors: selected $μ$SR studies. https://arxiv.org/abs/cond-mat/0408350

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