Daniel Parshall

Magnetic order in α−RuCl3 : A honeycomb-lattice quantum magnet with strong spin-orbit coupling

We report magnetic and thermodynamic properties of single crystal

Direct observation of dynamic charge stripes in La2–xSrxNiO4

\alpha

Competition between commensurate and incommensurate magnetic ordering in Fe1+yTe

-RuCl

Spin excitations in BaFe1.84CO0.16As2 superconductor observed by inelastic neutron scattering

_3

Spin wave damping arising from phase coexistence below Tc in colossal magnetoresistive La0.7Ca0.3MnO3

, in which the Ru

Measuring Phonon Lifetimes and Lattice Dynamics of Single-Crystal Methylammonium Lead Iodide with Neutron Triple-Axis Spectroscopy

^{3+}

Giant Electromechanical Coupling of Relaxor Ferroelectric Controlled by Polar Nanoregion Dynamics | NIST

(

Spin wave damping in colossal magnetoresistive La

4d^5

_{0.7}

) ion is in its low spin state and forms a honeycomb lattice. Two features are observed in both magnetic susceptibility and specific heat data; a sharp peak at 7~K and a broad hump near 10-15K. In addition, we observe a metamagnetic transition between 5~T and 10~T. Our neutron diffraction study of single crystal samples confirms that the low temperature peak in the specific heat is associated with a magnetic order with unit cell doubling along the honeycomb (100) direction, which is consistent with zigzag order, one of the types of magnetic order predicted within the framework of the Kitaev-Heisenberg model.

Ca

The insulator-to-metal transition continues to be a challenging subject, especially when electronic correlations are strong. In layered compounds, such as La2-xSrxNiO4 and La2-xBaxCuO4, the doped charge carriers can segregate into periodically spaced charge stripes separating narrow domains of antiferromagnetic order. Although there have been theoretical proposals of dynamically fluctuating stripes, direct spectroscopic evidence of charge-stripe fluctuations has been lacking. Here we report the detection of critical lattice fluctuations, driven by charge-stripe correlations, in La2-xSrxNiO4 using inelastic neutron scattering. This scattering is detected at large momentum transfers where the magnetic form factor suppresses the spin fluctuation signal. The lattice fluctuations associated with the dynamic charge stripes are narrow in q and broad in energy. They are strongest near the charge-stripe melting temperature. Our results open the way towards the quantitative theory of dynamic stripes and for directly detecting dynamical charge stripes in other strongly correlated systems, including high-temperature superconductors such as La2-xSrxCuO4.