Thermocouple installation

A thermocouple assembly which includes a plug having a pair of small diameter holes near one end thereof which are spaced a small distance apart to leave a thin quantity of plug material between the holes is presented. There are a pair of thermocouple wires extending through the different holes and with the outer ends of the wires joined to the thin quantity of plug material which lies between the holes to form a thermocouple junction

Effects of anisotropy in spin molecular-orbital coupling on effective spin models of trinuclear organometallic complexes

We consider layered decorated honeycomb lattices at two-thirds filling, as realized in some trinuclear organometallic complexes. Localized $S=1$ moments with a single-spin anisotropy emerge from the interplay of Coulomb repulsion and spin molecular-orbit coupling (SMOC). Magnetic anisotropies with bond dependent exchange couplings occur in the honeycomb layers when the direct intracluster exchange and the spin molecular-orbital coupling are both present. We find that the effective spin exchange model within the layers is an XXZ + 120$^\circ$ honeycomb quantum compass model. The intrinsic non-spherical symmetry of the multinuclear complexes leads to very different transverse and longitudinal spin molecular-orbital couplings, which greatly enhances the single-spin and exchange coupling anisotropies. The interlayer coupling is described by a XXZ model with anisotropic biquadratic terms. As the correlation strength increases the systems becomes increasingly one-dimensional. Thus, if the ratio of SMOC to the interlayer hopping is small this stabilizes the Haldane phase. However, as the ratio increases there is a quantum phase transition to the topologically trivial `$D$-phase'. We also predict a quantum phase transition from a Haldane phase to a magnetically ordered phase at sufficiently strong external magnetic fields.Comment: 22 pages, 11 figures. Final version of paper to be published in PRB. Important corrections to appendix

Heisenberg and Dzyaloshinskii-Moriya interactions controlled by molecular packing in tri-nuclear organometallic clusters

Motivated by recent synthetic and theoretical progress we consider magnetism in crystals of multi-nuclear organometallic complexes. We calculate the Heisenberg symmetric exchange and the Dzyaloshinskii-Moriya antisymmetric exchange. We show how, in the absence of spin-orbit coupling, the interplay of electronic correlations and quantum interference leads to a quasi-one dimensional effective spin model in a typical tri-nuclear complex, Mo$_3$S$_7$(dmit)$_3$, despite its underlying three dimensional band structure. We show that both intra- and inter-molecular spin-orbit coupling can cause an effective Dzyaloshinskii-Moriya interaction. Furthermore, we show that, even for an isolated pair of molecules the relative orientation of the molecules controls the nature of the Dzyaloshinskii-Moriya coupling. We show that interference effects also play a crucial role in determining the Dzyaloshinskii-Moriya interaction. Thus, we argue, that multi-nuclear organometallic complexes represent an ideal platform to investigate the effects of Dzyaloshinskii-Moriya interactions on quantum magnets.Comment: This update incorporates the corrections described in a recently submitted erratum. Changes are confined to sections IV.A and B. The conclusions of the paper are unchanged. 12 + 4 pages, 9 figure

Spin-orbit coupling in {Mo3_3S7_7(dmit)3_3}

Spin-orbit coupling in crystals is known to lead to unusual direction dependent exchange interactions, however understanding of the consequeces of such effects in molecular crystals is incomplete. Here we perform four component relativistic density functional theory computations on the multi-nuclear molecular crystal {Mo$_3$S$_7$(dmit)$_3$} and show that both intra- and inter-molecular spin-orbit coupling are significant. We determine a long-range relativistic single electron Hamiltonian from first principles by constructing Wannier spin-orbitals. We analyse the various contributions through the lens of group theory. Intermolecular spin-orbit couplings like those found here are known to lead to quantum spin-Hall and topological insulator phases on the 2D lattice formed by the tight-binding model predicted for a single layer of {Mo$_3$S$_7$(dmit)$_3$}

A phenomenological model of the superconducting state of the Bechgaard salts

We present a group theoretical analysis of the superconducting state of the Bechgaard salts, e.g., (TMTSF)_2PF_6 or (TMTSF)_2ClO_6. We show that there are eight symmetry distinct superconducting states. Of these only the (fully gapped, even frequency, p-wave, triplet) 'polar state' is consistent with the full range of the experiments on the Bechgaard salts. The gap of the polar state is d(k) (psi_uk,0,0), where psi_uk may be any odd parity function that is translationally invariant.Comment: 4 pages, no figure

Resisting the Trauma Story: Ethical Concerns in the Oral History Archive

This short article presents an oral history project undertaken with refugees resettled in Southwest Virginia. From this project has emerged an understanding of refugees as curators of a personal archive of stories. A birth-to-present oral history approach can resist the reductive trauma narratives refugees are often expected to tell, yet oral historians and archivists must also be aware of the story told by the archive framework itself. The authors explore the ethical challenges of amplifying oral histories from refugees in a way that inspires action without centering the trauma story, and leave readers with questions for reflection

A qualitative examination of police officers\u27 questioning of children about repeated events

For an offender to be convicted in relation to repeated child abuse, most jurisdictions require that each separate act be identified with reasonable precision with reference to time, place, or some other unique contextual detail (S v. R, 1989). The current study provided a qualitative examination of the way in which police officers assist children to identify and distinguish between occurrences of a repeated event. Field, as well as mock interviews (about an innocuous staged event) were examined, with child witnesses\u27 ages ranging from 3 to 16 years. Overall, several problems in the questioning were highlighted. These included: over-reliance on specific questions, use of \u27labels\u27 for occurrences without inquiring as to whether these were unique, and frequent shifting of the focus between occurrences. The implications of these findings are discussed. <br /