Vanishing RKKY interactions in Ce-based cage compounds.

We report the results of thermodynamic measurements in external magnetic field of the cubic Ce-based cage compounds CeCd(= Ni,Pd). Our analysis of the heat-capacity data shows that the Γdoublet is the ground state multiplet of the Ceions. Consequently, for the Γdoublet it can be theoretically shown that the Ruderman-Kittel-Kasuya-Yosida interaction between the localized Ce moments mediated by the conduction electrons, must vanish at temperatures much lower than the energy separating the ground state doublet from the first excited Γquartet.

Probing FeSi, a -electron topological Kondo insulator candidate, with magnetic field, pressure, and microwaves.

Recently, evidence for a conducting surface state (CSS) below 19 K was reported for the correlated -electron small gap semiconductor FeSi. In the work reported herein, the CSS and the bulk phase of FeSi were probed via electrical resistivity ρ measurements as a function of temperature , magnetic field to 60 T, and pressure to 7.6 GPa, and by means of a magnetic field-modulated microwave spectroscopy (MFMMS) technique.

Isoelectronic perturbations to --electron hybridization and the enhancement of hidden order in URuSi.

Electrical resistivity measurements were performed on single crystals of URu Os Si up to = 0.28 under hydrostatic pressure up to = 2 GPa. As the Os concentration, , is increased, 1) the lattice expands, creating an effective negative chemical pressure (); 2) the hidden-order (HO) phase is enhanced and the system is driven toward a large-moment antiferromagnetic (LMAFM) phase; and 3) less external pressure is required to induce the HO→LMAFM phase transition.

Optical signatures of Dirac nodal lines in NbAs.

Using polarized optical and magneto-optical spectroscopy, we have demonstrated universal aspects of electrodynamics associated with Dirac nodal lines that are found in several classes of unconventional intermetallic compounds. We investigated anisotropic electrodynamics of [Formula: see text] where the spin-orbit coupling (SOC) triggers energy gaps along the nodal lines. These gaps manifest as sharp steps in the optical conductivity spectra [Formula: see text] This behavior is followed by the linear power-law scaling of [Formula: see text] at higher frequencies, consistent with our theoretical analysis for dispersive Dirac nodal lines.

Phase diagram of URu Fe Si in high magnetic fields.

Electrical transport measurements were performed on URu Fe Si single-crystal specimens in high magnetic fields up to 45 T (DC fields) and 60 T (pulsed fields). We observed a systematic evolution of the critical fields for both the hidden-order (HO) and large-moment antiferromagnetic (LMAFM) phases and established the 3D phase diagram of In the HO phase, / scales with / and collapses onto a single curve. However, in the LMAFM phase, this single scaling relation is not satisfied.

Weak hybridization and isolated localized magnetic moments in the compounds CeT₂Cd₂₀ (T = Ni, Pd).

We report the physical properties of single crystals of the compounds CeT2Cd20 (T = Ni, Pd) that were grown in a molten Cd flux. Large separations of  ∼6.7-6.

Hole wave functions and transport with deazaadenines replacing adenines in DNA.

Transport of a hole along the base stack of DNA is relatively facile for a series of adenines (As) paired with thymines (Ts) or for a series of guanines (Gs) paired with cytosines (Cs). However, the speed at which a hole was found to travel was much too small to make useful semiconductor-type devices. Quite recently it was found that replacing one of the electronegative nitrogens (N3 or N7) with a carbon and a hydrogen, thus turning A into deazaadenine, increased the hole speed in what was A/T by a factor 30.