Changzhao Chen

Robust signatures detection of Majorana fermions in superconducting iron chains

We theoretically propose an optical means to detect Majorana fermions in superconducting iron (Fe) chains with a hybrid quantum dot-nanomechanical resonator system driven by two-tone fields, which is very different from the current tunneling spectroscopy experiments with electrical means. Based on the scheme, the phenomenon of Majorana modes induced transparency is demonstrated and a straightforward method to determine the quantum dot-Majorana fermions coupling strength is also presented. We further investigate the role of the nanomechanical resonator, and the resonator behaving as a phonon cavity enhances the exciton resonance spectrum, which is robust for detecting of Majorana fermions. The coherent optical spectrum affords a potential supplement to detecte Majorana fermions and supports Majorana fermions-based topological quantum computation in superconducting iron chains.

Inhomogeneous magnetic state induced by stress effect in epitaxial La0.67Sr0.33MnO3 films

La0.67Sr0.33MnO3 thin films with different thicknesses have been grown on [001] LaAlO3 substrates to investigate the structural, transport and magnetic variation induced by film thickness and lattice misfit. The x-ray diffraction results show the in-built stress evolution from a fully strained layer (~10 nm thickness) to a completely relaxed layer (~150 nm thickness), which can be well explained by the stress effect. Distinct transport and magnetic behaviors are observed, which depends strongly on film thickness. In particular, magnetization measurements show a non-uniform magnetic state in the strained film that we attribute to phase-separated clusters with ferromagnetic and antiferromagnetic domains induced by the epitaxial strain due to the lattice mismatch.