Strain-induced circular photogalvanic current in Dirac semimetal Cd3As2 film epitaxied on GaAs (111)B substrate

The Dirac semimetal (DSM) Cd3As2 has drawn great attention for exploring the novel quantum phenomena and high-speed optoelectronic applications. The circular photogalvanic effect (CPGE) current, resulting from the optically-excited spin...

Ultrahigh-Q Tunable Terahertz Absorber Based on Bulk Dirac Semimetal with Surface Lattice Resonance

In this paper, we present an easy-to-implement metamaterial absorber based on bulk Dirac semimetal (BDS). The proposed device not only obtains an ultrahigh quality factor (Q-factor) of 4133 and dynamic adjustability at high absorption, but also exhibits an excellent sensing performance with a figure of merit (FOM) of 4125. These outstanding properties are explained by the surface lattice resonance, which allows us to improve the quality factor significantly and control resonance wavelength precisely by tuning the unit cell periods, Fermi energy of the BDS, and structural parameters. Our findings can provide high-performance applications in terahertz filtering, detection, and biochemical sensing.

Vibrational Modes and Crystallographic Structure of Cd3As2 and (Cd1-xZnx)3As2 Epilayers

Low-temperature Raman scattering is used to study the crystal structure of molecular-beam epitaxially grown layers of the Dirac semimetal Cd3As2 and its related alloy (Cd1-xZnx)3As2. The combination of narrow-linewidth spectra, multiple growth directions and full polarization analysis allows improved accuracy in identifying the irreducible representation of over 57 Raman-active vibrations. Several disagreements with previous identifications are found. Structurally, the results agree with the centrosymmetric I41/acd space group of bulk-grown Cd3As2 and are clearly distinct from the Raman spectra of nanoscale platelets and wires. 3-fold twinning is seen in (112) Cd3As2 grown on (111) zincblende substrates corresponding to the three possible tetragonal orientations. In dilute (Cd1-xZnx)3As2, phonons have a frequency and scattering amplitude dependence on Zn concentration that is continuous with Cd3As2 but at least one frequency is absent at the alloy endpoint, preventing a simple one-mode description of the alloy phonon.