Structural Metastability and Fermi Surface Topology of SrAlSi.

SrAlSi crystallizes into either a semimetallic, CaAlSi-type, α phase or a superconducting, BaZnP-type, β phase. We explore possible transformations by employing pressure- and temperature-dependent free-energy calculations, vibrational spectral calculations, and room-temperature synchrotron powder X-ray diffraction (PXRD) measurements up to 14 GPa using a diamond anvil cell. Our theoretical and empirical analyses together with all reported baric and thermal events on both phases allow us to construct a preliminary - diagram of transformations.

Pressure dependence of room-temperature structural properties of CaAlSi.

We investigated the pressure dependence of the crystal structure of CaAlSiby means ofcalculations and room-temperature synchrotron x-ray powder diffraction.calculations reproduce satisfactorily the experimentally observed pressure-dependent structural evolution up to 3 GPa where the title system remains in the trigonalP3¯m1phase. In the pressure range 3-8 GPa, pressure evolution of the calculated in-plane lattice parameters is steeper than the observed.

Linear magnetoresistivity in layered semimetallic CaAlSi.

According to an earlier Abrikosov model, a positive, nonsaturating, linear magnetoresistivity (LMR) is expected in clean, low-carrier-density metals when measured at very low temperatures and under very high magnetic fields. Recently, a vast class of materials were shown to exhibit extraordinary high LMR but at conditions that deviate sharply from the above-mentioned Abrikosov-type conditions. Such deviations are often considered within either classical Parish-Littlewood scenario of random-conductivity network or within a quantum scenario of small-effective mass or low carriers at tiny pockets neighboring the Fermi surface.