Magnetic excitations in the topological semimetal YbMnSb2

Physical Review B American Physical Society 107:19 (2023) 195146

Authors:

Siobhan M Tobin, Jian-Rui Soh, Hao Su, Andrea Piovano, Anne Stunault, J Alberto Rodríguez-Velamazán, Yanfeng Guo, Andrew T Boothroyd

Abstract:

We report neutron scattering measurements on YbMnSb2 which shed light on the nature of the magnetic moments and their interaction with Dirac fermions. Using half-polarized neutron diffraction we measured the field-induced magnetization distribution in the paramagnetic phase and found that the magnetic moments are well localized on the Mn atoms. Using triple-axis neutron scattering we measured the magnon spectrum throughout the Brillouin zone in the antiferromagnetically ordered phase, and we determined the dominant exchange interactions from linear spin-wave theory. The analysis shows that the interlayer exchange is five times larger than in several related compounds containing Bi instead of Sb. We argue that the coupling between the Mn local magnetic moments and the topological band states is more important in YbMnSb2 than in the Bi compounds.

Meltable, Glass-Forming, Iron Zeolitic Imidazolate Frameworks.

Journal of the American Chemical Society 145:20 (2023) 11258-11264

Authors:

Luis León-Alcaide, Rasmus S Christensen, David A Keen, José L Jordá, Isaac Brotons-Alcázar, Alicia Forment-Aliaga, Guillermo Mínguez Espallargas

Abstract:

We describe the first meltable iron-based zeolitic imidazolate framework (ZIF), denoted MUV-24. This material, elusive from direct synthesis, is obtained from the thermal treatment of [Fe3(im)6(Him)2], which yields Fe(im)2 upon loss of the neutral imidazole molecules. Different crystalline phase transformations are observed upon further heating, until the material melts at 482 °C. Vitrification upon cooling of the liquid phase gives rise to the first Fe-metal-organic framework glass. X-ray total scattering experiments show that the tetrahedral environment of the crystalline solids is maintained in the glass, whereas nanoindentation measurements reveal an increase in Young's modulus, in agreement with stiffening upon vitrification.

Weyl metallic state induced by helical magnetic order

(2023)

Authors:

Jian-Rui Soh, Irián Sánchez-Ramírez, Xupeng Yang, Jinzhao Sun, Ivica Zivkovic, J Alberto Rodríguez-Velamazán, Oscar Fabelo, Anne Stunault, Alessandro Bombardi, Christian Balz, Manh Duc Le, Helen C Walker, J Hugo Dil, Dharmalingam Prabhakaran, Henrik M Rønnow, Fernando de Juan, Maia G Vergniory, Andrew T Boothroyd

The effect of magnetic order on longitudinal Tomonaga-Luttinger liquid spin dynamics in weakly coupled spin-1 2 chains

Physical Review B American Physical Society 107 (2023) 134425

Authors:

L Shen, A Alshemi, E Campillo, E Blackburn, P Steffens, M Boehm, Dharmalingam Prabhakaran, Andrew Boothroyd

Abstract:

The quantum many-body interactions in one-dimensional spin- 1 2 systems are subject to Tomonaga-Luttinger liquid (TLL) physics, which predict an array of multi-particle excitations that form continua in momentum-energy space. Here we use inelastic neutron spectroscopy to study the TLL spin dynamics in SrCo2V2O8, a compound which contains weakly coupled spin- 1 2 chains of Co atoms, at 0.05 K and in a longitudinal magnetic field up to 9.0 T. The measurements were performed above 3.9 T, where the ground state N´eel antiferromagnetic (AFM) order is completely suppressed, and the multi-particle excitations are exclusively of TLL type. In this region and below 7.0 T, the longitudinal TLL mode – psinon/antipsinon (P/AP) – is unexpectedly well described by a damped harmonic oscillator (DHO) while approaching the zone center defining the static spin-spin correlations. A non-DHO-type, continuum-like signal is seen at higher fields, but deviations from the ideal one-dimensional TLL still remain. This change in the P/AP mode coincides with the phase transition between the longitudinal spin density wave (LSDW) and transverse AFM order. Inside the LSDW state, the DHO-type P/AP spectral weight increases and the linewidth broadens as the magnetic order parameter decreases. These results reveal the impact of three-dimensional magnetic order on the TLL spin dynamics; they call for beyond the mean-field treatment for the interchain exchange interactions.

High-energy spin waves in the spin-1 square-lattice antiferromagnet La$_2$NiO$_4$

(2023)

Authors:

AN Petsch, NS Headings, D Prabhakaran, AI Kolesnikov, CD Frost, AT Boothroyd, R Coldea, SM Hayden