Model of lattice dynamics of Cd3As2 single crystals

Raman scattering (RS) in alpha-Cd3As2 single crystals has been studied. Its complex structure with the body centered tetragonal (b.c.t.) unit cell com prising as many as 160 atoms of the constituents is treated in terms of a m anifold of 16 imperfect zincblende-like units. the choice of InAs crystal a s the zincblende counterpart of the alpha-Cd3As2 crystal is discussed. A mo del of its lattice dynamics based on folding back dispersion branches of In As crystal into the b.c.t. Brillouin zone of alpha-Cd3As2 crystal is propos ed. The low frequency features observed in the RS spectra have been derived by folding TA branches of InAs along with Delta, Lambda and Sigma directio ns and mapping of TA(X) and TA(L) zincblende states onto the Gamma point of the b.c.t. Brillouin zone (BZ). Higher intensities of these modes correspo nd rather well with flatness of TA branches. The modes with frequencies hig her than 80 cm(-1) are derived from the folded, LA, TO and LO branches alon g Delta, Lambda and Sigma directions. Their lower intensities are attribute d to higher dispersion of LA, TO and LO branches.