A μSR Study of Magnetic Correlations in CeNiSn

Abstract

The formation of magnetic correlations in CeNiSn has been studied by muon spin rotation and relaxation (@RI spectroscopy covering the temperature range from 250K to 33 mK. Mainly a single crystalline sample was used. At high temperatures ( 5 2 K) a behaviour similar to that of a spin fluctuator like UA12 is observed, meaning that over the whole temperature range the paramagnetic moments fluctuate extremely fast ( 3 3 * 1014 Hz). Below 1 K the material exhibits properties typical for a paramagnet moving towards magnetic order, but no transition into long-range order could be observed down to the lowest measured temperature. The dependences of muon spin relaxation rate and muon spin precession frequency on external field (applied parallel to the a-axis) are unusual and indicate the formation of extended spin correlations up to short-range order.

On the low-temperature thermal properties and low-energy Fermi excitations in CeNiSn

“…This anomaly is likely related to the stabilization of magnetic correlations. The presence of magnetic correlations below 1 K was recently put on firm footing by #SR experiments [11].…”

“…So the square-T term in e~(T) should become small and the linear term is determined mainly by the volume dependence of T*. Taking into account the obvious relation N(Er),.~ 1/T* we find instead of (10) 8 In T* 2 (11) Here N(EF) is an additional factor arising in the multiband situation [-29]. It is believed that -01n T*/ 0 In V>> 1 [29], so the second term is dominant in the square brackets.…”

“…According to our approach the spin-fermion excitations give the dominant contribution to the low-temperature entropy. At present we cannot discuss the possible magnetic correlations at ultralow temperatures [11] and their contribution to the entropy and its derivatives, but we can interpret both the temperature and the field dependence of ~ above where euz is the corresponding ultralow-temperature contribution to the thermal expansion which can in principle be negative. So the spin-fermion contribution to the low-temperature entropy results in a linear + square T-dependence in zero-field behavior of the ev(T).…”

The competition between kondo and RKKY interaction in CeTSn compounds

“…This shows that there are no magnetic correlations detectable by gSR at temperatures where the gap seems to develop. At lower temperatures the relaxation rate started to increase together with a shift in spin rotation frequency [7]. This is shown in the left-hand part of Fig.…”

“…The other members of our "CeTSn"-team are F. J. Burghart, S. Flaschin, G. M. Kalvius, D. R. Noakes and R. W~ppling. The names of our collaborators on this subject can be found in [7,12,19,21]. This work was supported by the BMBF, Federal Republic of Germany under contract 03-KA4-TU1-9, by the Swedish National Science Research Council, by USDOE grant DE-FG05-88ER45353 and by Grant-in-Aid for Scientific Research, Japanese Ministry of Education, Science and Culture.…”