Temperature Dependence of the FIR Reflectance of LaSrGaO4

The reflectance of single crystal LaSrGaO4 has been measured from approx 50 to 40000 cm^-1 along the "a" and "c" axis. The optical properties have been calculated from a Kramers-Kronig analysis of the reflectance for both polarizations. The reflectance curves have been fit using a product of Lorentzian oscillators.Comment: 12 pages including 5 figures and 2 tables. Latex file, Requires elsart.sty file and eps

Quasi two dimensional spin correlations in the triangular lattice bilayer spin glass LuCoGaO4

We present a single crystal time of flight neutron scattering study of the static and dynamic spin correlations in LuCoGaO4, a quasi two dimensional dilute triangular lattice antiferromagnetic spin glass material. This system is based on Co2 ions that are randomly distributed on triangular bilayers within the YbFe2O4 type, hexagonal crystal structure. Antiferromagnetic short range two dimensional correlations at wave vectors Q 1 3,1 3,L develop within the bilayers at temperatures as high as TCW amp; 8764; 100 K and extend over roughly five unit cells at temperatures below Tg 19 K. These two dimensional static correlations are observed as diffuse rods of neutron scattering intensity along c and display a continuous spin freezing process in their energy dependence. Aside from exhibiting these typical spin glass characteristics, this insulating material reveals a novel gapped magnetic resonant spin excitation at E amp; 8764; 12 meV localized around Q 1 3,1 3,L . The temperature dependence of the spin gap associated with this two dimensional excitation correlates with the evolution of the static correlations into the spin glass state ground state.We associate it with the effect of the staggered exchange field acting on the Seff 1 2 Ising like doublet of the Co2 moment

Discovery of quantum phases in the Shastry-Sutherland compound SrCu2(BO3)2 under extreme conditions of field and pressure

The 2-dimensional layered oxide material SrCu2(BO3)2, long studied as a realization of the Shastry-Sutherland spin topology, exhibits a range of intriguing physics as a function of both hydrostatic pressure and magnetic field, with a still debated intermediate plaquette phase appearing at approximately 20 kbar and a possible deconfined critical point at higher pressure. Here, we employ a tunnel diode oscillator (TDO) technique to probe the behavior in the combined extreme conditions of high pressure, high magnetic field, and low temperature. We reveal an extensive phase space consisting of multiple magnetic analogs of the elusive supersolid phase and a magnetization plateau. In particular, a 10 × 2 supersolid and a 1/5 plateau, identified by infinite Projected Entangled Pair States (iPEPS) calculations, are found to rely on the presence of both magnetic and non-magnetic particles in the sea of dimer singlets. These states are best understood as descendants of the full-plaquette phase, the leading candidate for the intermediate phase of SrCu2(BO3)2

Discovery of quantum phases in the Shastry-Sutherland compound SrCu2(BO3)2 under extreme conditions of field and pressure

The 2-dimensional layered oxide material SrCu2(BO3)2, long studied as a realization of the Shastry-Sutherland spin topology, exhibits a range of intriguing physics as a function of both hydrostatic pressure and magnetic field, with a still debated intermediate plaquette phase appearing at approximately 20 kbar and a possible deconfined critical point at higher pressure. Here, we employ a tunnel diode oscillator (TDO) technique to probe the behavior in the combined extreme conditions of high pressure, high magnetic field, and low temperature. We reveal an extensive phase space consisting of multiple magnetic analogs of the elusive supersolid phase and a magnetization plateau. In particular, a 10 × 2 supersolid and a 1/5 plateau, identified by infinite Projected Entangled Pair States (iPEPS) calculations, are found to rely on the presence of both magnetic and non-magnetic particles in the sea of dimer singlets. These states are best understood as descendants of the full-plaquette phase, the leading candidate for the intermediate phase of SrCu2(BO3)2