arXiv subjects

D. J. Williams

Publications and source records attributed to D. J. Williams.

3 recordsLinked to original sources

arXiv2015

Magnetotransport of single crystalline NbAs

We report transport measurement in zero and applied magnetic field on a single crystal of NbAs. Transverse and longitudinal magnetoresistance in the plane of this tetragonal structure does not saturate up to 9 T. In the transverse configuration ($H \parallel c$, $I \perp c$) it is 230,000 \% at 2 K. The Hall coefficient changes sign from hole-like at room temperature to electron-like below $\sim$ 150 K. The electron carrier density and mobility calculated at 2 K based on a single band approximation are 1.8 x 10$^{19}$ cm$^{-3}$ and 3.5 x 10$^{5}$ cm$^2$/Vs, respectively. These values are similar to reported values for TaAs and NbP, and further emphasize that this class of noncentrosymmetric, transition-metal monopnictides is a promising family to explore the properties of Weyl semimetals and the consequences of their novel electronic structure.

cond-mat.mtrl-sci↗

arXiv2014

Investigation of the physical properties of the tetragonal CeMAl4Si2 (M = Rh, Ir, Pt) compounds

The synthesis, crystal structure, and physical properties studied by means of x-ray diffraction, magnetic, thermal and transport measurements of CeMAl$_{4}$Si$_{2}$ (M = Rh, Ir, Pt) are reported, along with the electronic structure calculations for LaMAl$_{4}$Si$_{2}$ (M = Rh, Ir, Pt). These materials adopt a tetragonal crystal structure (space group P4/mmm) comprised of BaAl$_4$ blocks, separated by MAl$_2$ units, stacked along the $c$-axis. Both CeRhAl$_{4}$Si$_{2}$ and CeIrAl$_{4}$Si$_{2}$ order antiferromagnetically below $T_{N1}$=14 and 16 K, respectively, and undergo a second antiferromagnetic transitition at lower temperature ($T_{N2}$=9 and 14 K, respectively). CePtAl$_{4}$Si$_{2}$ orders ferromagnetically below $T_C$ =3 K with an ordered moment of $μ_{sat}$=0.8 $μ_{B}$ for a magnetic field applied perpendicular to the $c$-axis. Electronic structure calculations reveal quasi-2D character of the Fermi surface.

cond-mat.str-el↗

arXiv2012

Temperature-concentration phase diagram of (Ca1-xLax)10(Pt3As8)(Fe2As2)5 superconductors

Single crystals of (Ca1-xLax)10(Pt3As8)(Fe2As2)5 (x = 0 to 0.182) superconductors have been grown and characterized by X-ray, microprobe, transport and thermodynamic measurements. Features in the magnetic susceptibility, specific heat and two kinks in the derivative of the electrical resistivity around 100 K in the x = 0 compound support the existence of decoupled structural and magnetic phase transitions. With La doping, the structural/magnetic phase transitions are suppressed and a half-dome of superconductivity with a maximal Tc around 26 K is observed in the temperature-concentration phase diagram.

cond-mat.supr-con↗