We have performed thermodynamic and neutron scattering measurements on the S=1/2 kagomé lattice antiferromagnet ZnCu3(OH)6Cl2. The susceptibility indicates a Curie-Weiss temperature of theta CW approximately = -300 K; however, no magnetic order is observed down to 50 mK. Inelastic neutron scattering reveals a spectrum of low energy spin excitations with no observable gap down to 0.1 meV. The specific heat at low-T follows a power law temperature dependence. These results suggest that an unusual spin liquid state with essentially gapless excitations is realized in this kagomé lattice system.

In two dimensional honeycomb ferromagnets, bosonic magnon quasiparticles (spin waves) may either behave as massless Dirac fermions or form topologically protected edge states. The key ingredient defining their nature is the next-nearest neighbor Dzyaloshinskii-Moriya (DM) interaction that breaks the inversion symmetry of the lattice and discriminates chirality of the associated spinwave excitations. Using inelastic neutron scattering, we find that spin waves of the insulating honeycomb ferromagnet CrI3 (TC = 61 K) have two distinctive bands of ferromagnetic excitations separated by a ∼4 meV gap at the Dirac points. These results can only be understood by considering a Heisenberg Hamiltonian with DM interaction, thus providing experimental evidence that spin waves in CrI3 can have robust topological properties potentially useful for dissipationless spintronic applications.

This study explores when wholly owned subsidiaries outperform joint ventures with local partners. In order to avoid the endogeneity problem inherent in foreign subsidiaries' operating mode decisions that might confound performance measurement, we employ the propensity score matching method, along with the difference‐in‐differences approach, and compare the performances of joint ventures turned wholly owned subsidiaries vis‐à‐vis continuing joint ventures. Based on foreign subsidiaries' financial data in China for 1998–2006, we find strong evidence that converted wholly owned subsidiaries outperform continuing joint ventures in industries characterized by high levels of intangible assets such as technology or brand, after controlling for factors that may affect the conversion decision. This finding is consistent with the prediction of transaction cost theory. Copyright © 2012 John Wiley & Sons, Ltd.