Universalities of anomalous properties in electron transport through different Z-shaped phosphorene nanoribbon devices

Aiming at improving the flexibility of designing the phosphorene-based nanodevices, we propose three kinds of Z-shaped phosphorene nanoribbons (ZPNRs), which are composed of two metallic nanoribbon electrodes and one semiconducting/metallic nanoribbon central region (CR). Many anomalous properties including the unexpected current increasing under the low bias voltage, the negative differential conductance, and the transition of the transport mechanism are found to be universal in different ZPNRs. Also, we find the current can be significantly suppressed by increasing the CR length, while no complete suppression can be induced by the increase of the CR width, indicating that the CR length and width will make different influences on the ZPNR transport. Moreover, the energy spectrums of two electrodes, the molecular energy levels of the CR, the transmission coefficients, and the transmission eigenstates are further calculated so as to clearly expound the anomalous properties and their universalities. We believe this research can provide a meaningful guidance for developing the phosphorene-based electronic devices.

Giant Spin Current Rectification Due to the Interplay of Negative Differential Conductance and a Non-Uniform Magnetic Field

In XXZ chains with large enough interactions, spin transport can be significantly suppressed when the bias of the dissipative driving becomes large enough. This phenomenon of negative differential conductance is caused by the formation of two oppositely polarized ferromagnetic domains at the edges of the chain. Here, we show that this many-body effect, combined with a non-uniform magnetic field, can allow for a high degree of control of the spin current. In particular, by studying all of the possible shapes of local magnetic fields potentials, we find that a configuration in which the magnetic field points up for half of the chain and down for the other half, can result in giant spin-current rectification, for example, up to 108 for a system with only 8 spins. Our results show clear indications that the rectification can increase with the system size.