H. C. Walker
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View article: Magnetic ground state and persistent spin fluctuations in triangular-lattice antiferromagnet NdZnAl$_{11}$O$_{19}$
Magnetic ground state and persistent spin fluctuations in triangular-lattice antiferromagnet NdZnAl$_{11}$O$_{19}$ Open
Rare-earth triangular-lattice magnets serve as an excellent platform for investigating exotic quantum magnetic phenomena. Recently, the hexaaluminate \cmao\ has been proposed to host a $U(1)$ Dirac quantum spin liquid state with dominant I…
View article: Spin correlations in the nematic quantum disordered state of FeSe
Spin correlations in the nematic quantum disordered state of FeSe Open
The quantum-disordered state in FeSe, intertwined with superconductivity and nematicity, has been a research focus in iron-based superconductors. However, the intrinsic spin excitations across the entire Brillouin zone in detwinned FeSe, c…
View article: Molecular alloying drives valence change in a van der Waals antiferromagnet
Molecular alloying drives valence change in a van der Waals antiferromagnet Open
View article: Neutron diffraction evidence of the 3-dimensional structure of Ba2MnTeO6 and misidentification of the triangular layers within the face-centred cubic lattice
Neutron diffraction evidence of the 3-dimensional structure of Ba2MnTeO6 and misidentification of the triangular layers within the face-centred cubic lattice Open
Arising from: J. Khatua et al.; Scientific Reports https://doi.org/10.1038/s41598-021-84876-5 (2021).
View article: Anomalous Quasielastic Scattering Contribution in the Centrosymmetric Multi-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="bold">q</mml:mi></mml:mrow></mml:math> Helimagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>SrFeO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>
Anomalous Quasielastic Scattering Contribution in the Centrosymmetric Multi- Helimagnet Open
Centrosymmetric compounds which host three-dimensional topological spin structures comprise a distinct subclass of materials in which multiple-q magnetic order is stabilized by anisotropy and bond frustration in contrast to the more common…
View article: Magnetic properties of the zigzag ladder compound <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>SrTb</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>
Magnetic properties of the zigzag ladder compound Open
We report on the properties of SrTb2O4, a frustrated zigzag ladder antiferromagnet, studied by single crystal neutron diffraction (with polarized neutrons in zero field and unpolarized neutrons in an applied magnetic field), as well as by …
View article: Magnetic properties of the zigzag ladder compound SrTb2O4
Magnetic properties of the zigzag ladder compound SrTb2O4 Open
We report on the properties of SrTb2O4, a frustrated zigzag ladder antiferromagnet, studied by single crystal neutron diffraction (with polarised neutrons in zero field and unpolarised neutrons in an applied magnetic field), as well as by …
View article: Anomalous quasielastic scattering contribution in the centrosymmetric multi-$\mathbf{q}$ helimagnet SrFeO$_3$
Anomalous quasielastic scattering contribution in the centrosymmetric multi-$\mathbf{q}$ helimagnet SrFeO$_3$ Open
Centrosymmetric compounds which host three-dimensional topological spin structures comprise a distinct subclass of materials in which multiple-$\mathbf{q}$ magnetic order is stabilized by anisotropy and bond frustration in contrast to the …
View article: Magnetic diffuse scattering of the $S$ = 5/2 fcc antiferromagnets Ba$_2$MnTeO$_6$ and Ba$_2$MnWO$_6$
Magnetic diffuse scattering of the $S$ = 5/2 fcc antiferromagnets Ba$_2$MnTeO$_6$ and Ba$_2$MnWO$_6$ Open
We have investigated the magnetic diffuse scattering of isostructural $S$ = 5/2 fcc antiferromagnets Ba$_2$MnTeO$_6$ and Ba$_2$MnWO$_6$ using polarized neutrons. Both materials display short-range correlated magnetism above their respectiv…
View article: Uncovering the phonon spectra and lattice dynamics of plastically deformable InSe van der Waals crystals
Uncovering the phonon spectra and lattice dynamics of plastically deformable InSe van der Waals crystals Open
Stacking two-dimensional (2D) van der Waals (vdW) materials in a layered bulk structure provides an appealing platform for the emergence of exotic physical properties. As a vdW crystal with exceptional plasticity, InSe offers the opportuni…
View article: Neutron Scattering Studies on the High-$T_c$ Superconductor La$_3$Ni$_2$O$_{7-δ}$ at Ambient Pressure
Neutron Scattering Studies on the High-$T_c$ Superconductor La$_3$Ni$_2$O$_{7-δ}$ at Ambient Pressure Open
After several decades of studies of high-temperature superconductivity, there is no compelling theory for the mechanism yet; however, the spin fluctuations have been widely believed to play a crucial role in forming the superconducting Coo…
View article: Weyl metallic state induced by helical magnetic order
Weyl metallic state induced by helical magnetic order Open
In the rapidly expanding field of topological materials there is growing interest in systems whose topological electronic band features can be induced or controlled by magnetism. Magnetic Weyl semimetals, which contain linear band crossing…
View article: Nematic quantum disordered state in FeSe
Nematic quantum disordered state in FeSe Open
The unusual quantum-disordered magnetic ground state intertwined with superconductivity and electronic nematicity in FeSe has been a research focus in iron-based superconductors. However, the intrinsic spin excitations across the entire Br…
View article: Structure, Spin Correlations, and Magnetism of the <i>S</i> = 1/2 Square-Lattice Antiferromagnet Sr<sub>2</sub>CuTe<sub>1–<i>x</i></sub>W<sub><i>x</i></sub>O<sub>6</sub> (0 ≤ <i>x</i> ≤ 1)
Structure, Spin Correlations, and Magnetism of the <i>S</i> = 1/2 Square-Lattice Antiferromagnet Sr<sub>2</sub>CuTe<sub>1–<i>x</i></sub>W<sub><i>x</i></sub>O<sub>6</sub> (0 ≤ <i>x</i> ≤ 1) Open
Quantum spin liquids are highly entangled magnetic states with exotic properties. The S = 1/2 square-lattice Heisenberg model is one of the foundational models in frustrated magnetism with a predicted, but never observed, quantum sp…
View article: On (not) deriving the entropy of barocaloric phase transitions from crystallography and neutron spectroscopy
On (not) deriving the entropy of barocaloric phase transitions from crystallography and neutron spectroscopy Open
We consider well-known signatures of disorder in crystallographic and inelastic neutron scattering data. We show that these can arise from different types of disorder, corresponding to different values of the system entropy. Correlating th…
View article: Structure, spin correlations and magnetism of the $S = 1/2$ square-lattice antiferromagnet Sr$_2$CuTe$_{1-x}$W$_x$O$_6$ ($0 \leq x \leq 1$)
Structure, spin correlations and magnetism of the $S = 1/2$ square-lattice antiferromagnet Sr$_2$CuTe$_{1-x}$W$_x$O$_6$ ($0 \leq x \leq 1$) Open
Quantum spin liquids are highly entangled magnetic states with exotic properties. The $S = 1/2$ square-lattice Heisenberg model is one of the foundational models in frustrated magnetism with a predicted, but never observed, quantum spin li…
View article: Automated potential development workflow: Application to BaZrO3
Automated potential development workflow: Application to BaZrO3 Open
We present a Python workflow, Automated Potential Development (APD), for automating the development of interatomic potentials, including calculation of density functional theory (DFT) fitting data, optimization of potentials, and potential…
View article: On (not) deriving the entropy of barocaloric phase transitions from crystallography and neutron spectroscopy
On (not) deriving the entropy of barocaloric phase transitions from crystallography and neutron spectroscopy Open
We review well-known signatures of disorder in crystallographic and inelastic neutron scattering data. We show that these can arise from different types of disorder, corresponding to different values of the system entropy. Correlating the …
View article: Author Correction: Optimizing the dynamic pair distribution function method for inelastic neutron spectrometry
Author Correction: Optimizing the dynamic pair distribution function method for inelastic neutron spectrometry Open
View article: Weyl metallic state induced by helical magnetic order
Weyl metallic state induced by helical magnetic order Open
In the rapidly expanding field of topological materials there is growing interest in systems whose topological electronic band features can be induced or controlled by magnetism. Magnetic Weyl semimetals, which contain linear band crossing…
View article: Spin Fluctuations in Sr$_{1.8}$La$_{0.2}$RuO$_4$
Spin Fluctuations in Sr$_{1.8}$La$_{0.2}$RuO$_4$ Open
We use inelastic neutron scattering to study spin fluctuations in Sr$_{1.8}$La$_{0.2}$RuO$_4$, where Lanthanum doping triggers a Lifshitz transition by pushing the van Hove singularity in the $γ$ band to the Fermi energy. Strong spin fluct…
View article: Structure and dynamics of the negative thermal expansion material Cd(CN)$_2$ under pressure
Structure and dynamics of the negative thermal expansion material Cd(CN)$_2$ under pressure Open
We use a combination of variable-temperature / variable-pressure neutron powder diffraction, variable-pressure inelastic neutron scattering, and quantum chemical calculations to interrogate the behaviour of the negative thermal expansion (…
View article: Dynamics in the ordered and disordered phases of barocaloric adamantane
Dynamics in the ordered and disordered phases of barocaloric adamantane Open
The archetypal plastic crystal adamantane has ideal properties for low-temperature barocaloric cooling. Its large entropy change is explained in terms of differences between the molecular dynamics in the ordered and disordered phases.
View article: Origin of the Large Entropy Change in the Molecular Caloric and Ferroelectric Ammonium Sulfate (Adv. Funct. Mater. 45/2022)
Origin of the Large Entropy Change in the Molecular Caloric and Ferroelectric Ammonium Sulfate (Adv. Funct. Mater. 45/2022) Open
Molecular Caloric In article number 2207717, Phillips and co-workers show that the large entropy change in the caloric material ammonium sulfate arises from librations of the ammonium ions in flat-bottomed, “bathtub-shaped” potential wells…
View article: Dynamics in the ordered and disordered phases of barocaloric adamantane
Dynamics in the ordered and disordered phases of barocaloric adamantane Open
High-entropy order-disorder phase transitions can be used for efficient and eco-friendly barocaloric solid-state cooling. Here the barocaloric effect is reported in an archetypal plastic crystal, adamantane. Adamantane has a colossal isoth…
View article: Gapless triangular-lattice spin-liquid candidate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>PrZnAl</mml:mi><mml:mn>11</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>19</mml:mn></mml:msub></mml:mrow></mml:math>
Gapless triangular-lattice spin-liquid candidate Open
A quantum spin liquid (QSL) is an exotic state in which electron spins are highly entangled, yet keep fluctuating even at zero temperature. Experimental realization of model QSLs has been challenging due to imperfections, such as antisite …
View article: Quantum critical spin-liquid-like behavior in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>S</mml:mi><mml:mo>=</mml:mo><mml:mfrac><mml:mn>1</mml:mn><mml:mn>2</mml:mn></mml:mfrac></mml:mrow></mml:math> quasikagome-lattice compound <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">CeRh</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">Pd</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mi>Sn</mml:mi></mml:math> investigated using muon spin relaxation and neutron scattering
Quantum critical spin-liquid-like behavior in the quasikagome-lattice compound investigated using muon spin relaxation and neutron scattering Open
We present the results of muon spin relaxation ($\\mu$SR) and neutron\nscattering on the Ce-based quasikagome lattice CeRh$_{1-x}$Pd$_{x}$Sn ($x=0.1$\nto 0.75). Our ZF-$\\mu$SR results reveal the absence of static long-range\nmagnetic orde…
View article: Origin of the Large Entropy Change in the Molecular Caloric and Ferroelectric Ammonium Sulfate
Origin of the Large Entropy Change in the Molecular Caloric and Ferroelectric Ammonium Sulfate Open
The deceptively simple inorganic salt ammonium sulfate undergoes a ferroelectric phase transition associated with a very large entropy change and both electrocaloric and barocaloric functionality. While the structural origins of the electr…
View article: Frustrated magnetic interactions in FeSe
Frustrated magnetic interactions in FeSe Open
The structurally simplest high-temperature superconductor FeSe exhibits an intriguing superconducting nematic paramagnetic phase with unusual spin excitation spectra that are different from typical spin waves; thus, determining its effecti…
View article: Pressure dependence of rotational dynamics in barocaloric ammonium sulfate
Pressure dependence of rotational dynamics in barocaloric ammonium sulfate Open
Solid-state cooling using barocaloric materials is a promising avenue for eco-friendly, inexpensive and highly efficient cooling. To design barocaloric compounds ready for deployment, it is essential to understand their thermodynamic behav…