Crystal growth and anisotropic properties of CeTAs2 (T = Ag and Cu) and extreme magnetoresistance compounds ASi2 (A = Mo and W)

The close proximity of 4f level to the Fermi energy in Ce-based compounds leads to many interesting physical properties like heavy fermion, mixed valence, quantum critical behavior etc. CeTAs2 (T = Cu, Ag) have drawn much attention due to their unusual structural and physical properties. CeCuAs2 is found to crystallize in HfCuSi2 type tetragonal crystal structure, with space group P4/nmm (#129), whereas CeAgAs2 does not crystallize in exactly HfCuSi2 type structure, rather it crystallizes in the four-fold superstructure with a space group Pmca (#57). I will present the crystal growth and anisotropic physical properties of these compounds.

Recently, unsaturated extremely large positive magnetoresistance in some particular class of nonmagnetic (diamagnetic) semimetals such as, compensated, Dirac and Weyl semimetals has drawn considerable interest. Nearly compensation of charge carriers and extremely large carrier mobility leads to such extremely large magnetoresistance (XMR) of ~ 105 % in those semimetals. The study of the Fermi surface topology by means of de Haas-van Alphen (dHvA) and Shubnikov-de Haas (SdH) quantum oscillations on extremely high quality single crystals unveils many interesting physics associated with these semimetals. In the quest for searching the materials exhibiting such phenomena, we have grown a high quality single crystal of MoSi2 and WSi2 by Czochralski pulling in tetra arc furnace. Single crystal of MoSi2 and WSi2 crystallizes in tetragonal structure with space group I4/mmm (#139). The anisotropic magneto-transport properties of MoSi2 will be discussed in the seminar.