We present the results of an exact diagonalization study of the spin-1/2 Heisenberg antiferromagnet on a two-dimensional version of the pyrochlore lattice, also known as the square lattice with crossings or the checkerboard lattice. Examining the low energy spectra for systems of up to 24 spins, we find that all clusters studied have non-degenerate ground states with total spin zero, and big en...

Lead-rich intermediate phases, in particular Pt,,Pb and PbO, are found to form on Pt(ll1) atop Ti-buffered Si substrates prior to formation of Pb(Zr, -*TiX)O3 (PZT) thin films. Pt,_,Pb is a [ill] textured transient intermetallic phase that nucleates PZT[111] texture. PbO is a [OOl] textured layer compound that nucleates PZT[100] texture. The formation conditions and lattice matching of these in...

Recently, significant interest has emerged in fabricated systems that mimic the behavior of geometrically frustrated materials. We present the full realization of such an artificial spin ice system on a two-dimensional kagome lattice and we demonstrate rigid adherence to the local ice rule by directly counting individual pseudospins. The resulting spin configurations show not only local ice rul...

The spin-lattice coupling plays an important role in strongly frustrated magnets. In ZnCr2O4, an excellent realization of the Heisenberg antiferromagnet on the pyrochlore network, a lattice distortion relieves the geometrical frustration through a spin-Peierls-like phase transition at T(c)=12.5 K. Conversely, spin correlations strongly influence the elastic properties of a frustrated magnet. By...

Analyses for columbium in pyrochlore ores from North Bay, Ontario, have been made successfully by using o-ray fluorescence techniques. rt was necessary to use, as in methods of optical spectroscopy) an internal standard for this work. The choice of a suitable internal standard for a particular metal in a specific mineral association or ore-t).pe requires consideration of the characteristic r-ra...

We have studied spin freezing in the diluted spin ice compound Dy22xYxTi2O7 where the nonmagnetic Y ions replace the magnetic Dy ions on the frustrated pyrochlore lattice. Magnetic ac and dc susceptibility data are presented with an analysis of relaxation times for dilutions of x50, 0.1, 0.2, and 0.4. Site dilution apparently decreases the relative number of spins participating in the icelike f...

Motivated by numerical evidence of the valence-bond ground state of the two-dimensional Heisenberg pyrochlore lattice, we argue using a t-J model that it evolves under doping into novel phases characterized by superconductivity coexisting with the underlying valence-bond solid order. A fermionic mean-field theory supplemented by exact diagonalization results provide strong arguments in favor of...

Abstract The molar heat capacity of terbium hafnate with a pyrochlore structure was measured by relaxation and adiabatic calorimetry. smoothed values the were used to calculate thermodynamic functions in temperature range 6–330 K. general form Schottky anomaly determined.