arXiv subjects

A. D. Hillier

Publications and source records attributed to A. D. Hillier.

148 records · Page 9Linked to original sources

arXiv2004

$μ$SR study of the quantum dynamics in the frustrated $S=3/2$ kagome bilayers

We present $μ$SR experiments in the $S=3/2$ kagome bilayer compound Ba$_{2}$Sn$_{2}$ZnGa$_{10-7p}$Cr$_{7p}$O$_{22}$ (BSZCGO$(p)$) and compare it to the isostructural SrCr$_{9p}$Ga$_{12-9p}$O$_{19}$ (SCGO$(p)$), including for the latter new results for $p\geq0.89$. Quantum-dynamical low energy magnetic excitations are evidenced in this novel compound. We study the evolution of the muon relaxation rate with $p$, $T$ and field. A phenomenological model for the muon relaxation based on sporadic dynamics due to spin excitations in a singlet sea proposed by Uemura \emph{et al.} [Phys. Rev. Lett. \textbf{73}, 3306 (1994)]. is extended to all fields and $T$-range. Its connexion to the RVB picture is discussed, and we argue that such coherent states might mediate the interactions between "impurities" which induce the spin glass freezing.

cond-mat.str-el↗

arXiv2003

Exposing the spin glass ground state of the non-superconducting La$_{2-x}$Sr$_x$Cu$_{1-y}$Zn$_{y}$O$_4$ high-$T_c$ oxide

We have studied the spin glass behaviour of non-superconducting La$_{2-x}$Sr$_x$Cu$_{0.95}$Zn$_{0.05}$O$_4$ ($x=0.10-0.22$). As in the superconducting analogues of these samples the spin glass transition temperature $T_g$ decreases with increasing $x$, and vanishes at $x=0.19$. A local enhancement in $T_g$ at $x=0.12$ is also observed and attributed to stripe ordering. The disappearance of $T_g$ for $x\geq0.19$ is discussed in terms of a quantum phase transition.

cond-mat.supr-con↗

arXiv2003

A Reduced Moment Magnetic Ordering in a Kondo Lattice Compound: Ce8pd24ga

The magnetic ground state of the antiferromagnet Kondo lattice compound Ce8Pd24Ga has been investigated using neutron powder diffraction, inelastic neutron scattering and zero-field muon spin relaxation measurements. The neutron diffraction analysis, below TN (3.6(0.2)K), reveals a commensurate type-C antiferromagnetic structure with the ordered state magnetic moment of \~0.36 mB/Ce-atom along the cubic <111> direction. The analysis of the inelastic neutron scattering (INS) data based on the crystal field (CF) model reveals a doublet ground state with a ground state moment of 1.29 mB/Ce-atom. The observed magnetic moment from neutron diffraction, which is small compared to the expected value from CF-analysis, is attributed to screening of the local Ce moment by the Kondo effect. This is supported by the observed Kondo-type resistivity and a small change in the entropy of Ce8Pd24Ga at TN. The zero-field muon spin relaxation rate exhibits a sharp increase below TN indicating ordering of Ce moments, in agreement with the neutron diffraction data. The present studies reveal that the physical properties of Ce8Pd24Ga are governed by the onsite Kondo compensation, the moment stabilizing intersite RKKY interaction and the crystal field effect.

cond-mat.str-el↗

arXiv2002

The application of the NeXus data format to ISIS muon data

Although originally designed by and for the use of the Neutron and X-ray communities, the flexibility of the NeXus data format makes it equally suitable for storing data gathered from MuSR experiments. Furthermore, its use should open up the possibility of sharing software beyond the immediate muon community; giving access to the many tools that are already in existence for manipulating NeXus and HDF based files. This paper explores the development of the NeXus format for storing ISIS muon data and the associated experimental conditions. The design of an Instrument Definition for the ISIS muon instruments is described and the implementation of an application to translate the present ISIS raw data format to the NeXus format presented. The development of a common muon data format is a topic of active discussion within the muon community; with this in mind, the suitability of NeXus and, in particular, the ISIS Instrument Definition for general application is considered. A number of applications that have been developed to exploit the flexibility of the ISIS muon NeXus file format are described and a scheme for enabling web based browsing and analysis of experiment data is introduced.

cond-mat↗