Local magnetism, magnetic order and spin freezing in the 'nonmetallic metal' FeCrAs.
Journal of physics. Condensed matter : an Institute of Physics journal 31:28 (2019) 285803-285803
Abstract:
We present the results of x-ray scattering and muon-spin relaxation ([Formula: see text]SR) measurements on the iron-pnictide compound FeCrAs. Polarized non-resonant magnetic x-ray scattering results reveal the 120° periodicity expected from the suggested three-fold symmetric, non-collinear antiferromagnetic structure. [Formula: see text]SR measurements indicate a magnetically ordered phase throughout the bulk of the material below [Formula: see text] K. There are signs of fluctuating magnetism in a narrow range of temperatures above [Formula: see text] involving low-energy excitations, while at temperatures well below [Formula: see text] behaviour characteristic of freezing of dynamics is observed, likely reflecting the effect of disorder in our polycrystalline sample. Using density functional theory we propose a distinct muon stopping site in this compound and assess the degree of distortion induced by the implanted muon.Evidence for a J(eff)=0 ground state and defect-induced spin glass behavior in the pyrochlore osmate Y2Os2O7
PHYSICAL REVIEW B 99:17 (2019) ARTN 174442
Phase Transitions, Broken Symmetry and the Renormalization Group
Chapter in The Routledge Handbook of Emergence, Taylor & Francis (2019) 237-247
Spin dynamics and field-induced magnetic phase transition in the honeycomb Kitaev magnet α-Li2IrO3
Physical Review B American Physical Society 99:5 (2019) 054426
Abstract:
The layered honeycomb iridate α-Li2IrO3 displays an incommensurate magnetic structure with counterrotating moments on nearest-neighbor sites, proposed to be stabilized by strongly frustrated anisotropic Kitaev interactions between spin-orbit entangled Ir4+ magnetic moments. Here we report powder inelastic neutron scattering measurements that observe sharply dispersive low-energy magnetic excitations centered at the magnetic ordering wave vector, attributed to Goldstone excitations of the incommensurate order, as well as an additional intense mode above a gap 2.3 meV. Zero-field muon-spin relaxation measurements show clear oscillations in the muon polarization below the Néel temperature TN 15 K with a time-dependent profile consistent with bulk incommensurate long-range magnetism. Pulsed-field magnetization measurements observe that only about half the saturation magnetization value is reached at the maximum field of 64 T. A clear anomaly near 25 T indicates a transition to a phase with reduced susceptibility. The transition field has a Zeeman energy comparable to the zero-field gapped mode, suggesting gap suppression as a possible mechanism for the field-induced transition.Unconventional field-induced spin gap in an S=1/2 Chiral staggered chain
Physical Review Letters American Physical Society 122 (2019) 057207