Neutron-diffraction study of the evolution of antiferromagnetic order inUPt3doped with Pd

Magnetic Quantum Critical Point and Superconductivity inUPt3Doped with Pd

“…As a first step, we have analyzed the mSR spectra using a Gaussian-damped depolarization function P G ͑t͒ A G cos͑vt͒ exp͑2D 2 t 2 ͞2͒, where A G is the asymmetry, v 2pn m , and D is the Gaussian damping rate. At the highest temperatures, D attains a T independent value of ϳ0.06 ms 21 , which is consistent with depolarization due to static 195 Pt nuclear moments [15]. Upon lowering T , D rises progressively, which points to the presence of an additional source of internal dipolar magnetic fields.…”

“…2 the T dependence of l E is shown for all three samples. At the highest temperatures l E is very small ϳ0.003 ms 21 and essentially T independent. Upon lowering T , l E increases, as the additional source of magnetism emerges.…”

“…Accurate determination of the rates for the samples with x 0.007 and 0.008 was made possible by the use of a kicker device, which ensures that only one muon at a time is present in the sample and that no other muons are present in the spectrometer [27]. This so-called MORE (muons on request) mode allows one to extend the mSR time window to 20 ms, with virtually no accidental background, making it possible to measure relaxation rates as small as 0.001 ms 21 . When positive muons come to rest in the sample they start to precess around the local field, B loc , with a precession frequency n m g m B loc (g m ͞2p 135.5 MHz͞T is the muon gyromagnetic ratio).…”

“…Neutron-diffraction experiments [21] show that SMAF is robust upon alloying with Pd and persists 0031-9007͞00͞85 (14)͞3005 (4) [21], specific heat ͑ᮀ͒ [17,21], and mSR ͑᭡͒ (Ref. [15] and this work).…”

“…1). Neutrondiffraction experiments [20,21] show that at optimal doping ͑x 0.05, T N 6 K͒ the ordered moment of the so-termed large-moment antiferromagnetic phase (LMAF) is substantial, m ͑0.63 6 0.05͒m B per U atom, and that the magnetic order parameter is conventional. The magnetic structure consists of a doubling of the nuclear unit cell (space group P6 3 ͞mmc) along the a ‫ء‬ axis, with the moments pointing along a ‫ء‬ .…”