Daniel McNally

CaMn2Sb2: Spin waves on a frustrated antiferromagnetic honeycomb lattice

We present inelastic neutron scattering measurements of the antiferromagnetic insulator CaMn2Sb2:, which consists of corrugated honeycomb layers of Mn. The dispersion of magnetic excitations has been measured along the H and L directions in reciprocal space, with a maximum excitation energy of ≈ 24 meV. These excitations are well described by spin waves in a Heisenberg model, including first and second neighbor exchange interactions, J1 and J2, in the Mn plane and also an exchange interaction between planes. The determined ratio J2/J1 ≈ 1/6 suggests that CaMn2Sb2: is the first example of a compound that lies very close to the mean field tricritical point, known for the classical Heisenberg model on the honeycomb lattice, where the N´eel phase and two different spiral phases coexist. The magnitude of the determined exchange interactions reveal a mean field ordering temperature ≈ 4 times larger than the reported N´eel temperature TN = 85 K, suggesting significant frustration arising from proximity to the tricritical point.

From Hund's insulator to Fermi liquid: Optical spectroscopy study of K doping in BaMn 2 As 2

We present optical transmission measurements that reveal a charge gap of 0.86 eV in the local moment antiferromagnetic insulator BaMn

Combined computational and experimental investigation of the La2CuO4–xSx (0 ≤ x ≤ 4) quaternary system

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Magnetic and structural phase diagram of CaMn2Sb2

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Origin of the Charge Gap in LaMnPO

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Combined computational and experimental investigation of the La-Cu-S-O quaternary system

, an order of magnitude larger than previously reported. Density functional theory plus dynamical mean field theory (DFT+DMFT) calculations correctly reproduce this charge gap only when a strong Hunds coupling is considered. Thus, BaMn

Controlling the magnetism of the Mott insulator LaTiO 3 by interface engineering

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Electron-phonon coupling and polaronic effects in the high- T c superconductor Ba 1- x K x BiO 3

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Anisotropic evolution of charge/spin excitations in square-planar cuprates

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Robustness of the insulating band structure of BaBiO3 films in the ultrathin limit

is a member of a wider class of Mn pnictide compounds that are Mott-Hunds insulators. We also present optical reflectance for metallic 2% K doped BaMn