Indirect exchange interaction in parabolic symmetry-induced zero gap semiconductors

Effective exchange interaction and Curie temperature in magnetic semiconductors

Based on a previously reported double-resonance mechanism, we present an analytical expression of the effective exchange interaction between impurity moments of transition-metal elements introduced in semiconductors. It is shown that the exchange interaction is enhanced by several orders of magnitude as compared with the ordinary RKKY interaction when the Fermi level and impurity states are clo...

Magnetic Ordering in Gd Monopnictides: Indirect Exchange Versus Superexchange Interaction

Emergence of topological semimetals in gap closing in semiconductors without inversion symmetry

A band gap for electronic states in crystals governs various properties of solids, such as transport, optical, and magnetic properties. Its estimation and control have been an important issue in solid-state physics. The band gap can be controlled externally by various parameters, such as pressure, atomic compositions, and external field. Sometimes, the gap even collapses by tuning some paramete...

Genetic-algorithm discovery of a direct-gap and optically allowed superstructure from indirect-gap Si and Ge semiconductors.

Combining two indirect-gap materials-with different electronic and optical gaps-to create a direct gap material represents an ongoing theoretical challenge with potentially rewarding practical implications, such as optoelectronics integration on a single wafer. We provide an unexpected solution to this classic problem, by spatially melding two indirect-gap materials (Si and Ge) into one strongl...

Exchange-coupling-induced symmetry breaking in topological insulators.

An exchange gap in the Dirac surface states of a topological insulator (TI) is necessary for observing the predicted unique features such as the topological magnetoelectric effect as well as to confine Majorana fermions. We experimentally demonstrate proximity-induced ferromagnetism in a TI, combining a ferromagnetic insulator EuS layer with Bi(2)Se(3), without introducing defects. By magnetic ...