Tuning the magnetic ordering driven by cationic antisite defects in the Li(ZnMn)As system

The electronic structure and magnetic properties of Li(ZnMn)As with antisite defects have been investigated by using first-principles calculations within the Perdew-Burke-Ernzerhof generalized gradient approximation. The cation antisite defect induced by Zn substitution for As was considered. Mn-3d, As-4p, Zn-4s, and Zn-4p were involved in the formation of d-sp hybrid orbitals, which enhanced the non-localized properties of Mn-3d electrons and provided a channel of Mn(↑)-As(↓)-ZnAs(↓)-Mn(↑) for indirect exchange of electrons between the magnetic ions. The antisite defect of Zn-substituted As belonged to the acceptor doping, rendering the compound p-type characteristics. The existence of the extra free hole carriers regulated the magnetic ordering transition. The ferromagnetic coupling between the Mn magnetic dopants was more favorable in the system with an antisite defect. In this paper, a novel type of dilute magnetic semiconductor with controllable carriers was designed and the mechanism of ferromagnetic coupling was revealed, which provided a theoretical reference for the subsequent studies.

Geometry, induced magnetism and modified electronic behaviors for magnetic atom adsorption on antimonene nanotubes

The detailed first-principles calculations show that TM adsorption can imprint versatile magnetism into antimonene nanotubes. A significant carrier polarity and spin polarity of mobility as well as the magneto-electric material property are found.

Magneto-electronic properties, carrier mobility and strain effects of InSe nanoribbon

The monolayer InSe has been successfully fabricated recently and studied intensely. Here, we investigate the geometrical stability and various physical properties such as electronic and magnetic feature, carrier mobility and strain effects for InSe nanoribbons. Our calculations show that armchair nanoribbons, regardless of the bare-edged or H-saturated ones, are semiconductors with an indirect bandgaps, but the bandgap size is increased greatly by H-saturation. Their electron mobility is predicted to be moderately large (from ~10² to ~10³ cm² V^-1 s^-1) with the holes being less mobile for wider ribbons, and the carrier polarity phenomenon becomes more prominently for H-saturation. The zigzag InSe nanoribbons are found to be magnetic metals with a bigger magnetic moment and the ferromagnetic ground state at the single edge. The magnetism stems from unpaired electrons at the In-rich edge. More interestingly, it is found that the externally applied mechanical strain can effectively tune the spin polarization efficiency at the Fermi level to two stepwise stages, suggesting that the strain can act as a tool for developing a mechanical switch to control spin-polarized transport under lower bias. The detailed analysis suggests that this strain-tuning mechanism can be attributed to the ionic and covalent bond-configuration competition due to the strain-induced bond-length alterations, which leads to the unpaired electron redistribution in magnetic atoms or vanishing.

Surprisingly good thermoelectric performance of a black phosphorus/blue phosphorus van der Waals heterostructure

Thermoelectric properties of a black phosphorus/blue phosphorus van der Waals heterostructure are investigated by using first-principles calculations and Boltzmann transport theory for both electrons and phonons.

Strain-induced rich magnetic phase transitions and enhancement of magnetic stability for O-terminated h-BN nanoribbons

Mono-layered h-BN and its derivatives are very important low-dimensional materials, which have been widely investigated so far. Here, we theoretically study the structural stability and magneto-electronic properties of oxygen (O) terminated zigzag-edged h-BN nanoribbons, especially focusing on strain tuning effects. The O dimerization at the B edge of the ribbon enhances the system stability greatly. A Poisson ratio of 0.2 and bearing a strain more than 20% can be reached. In the absence of strain, the O-terminated ribbon is a magnetic metal. However, the rich magnetic phase transitions among the non-magnetic metal, a spin gapless semiconductor, and a wide-gap half-metal can be realized continuously by applying strain in the ferromagnetic state. Thus, based on such a material feature, we can design a magnetic switch device which can work between the magnetic and non-magnetic states by strain modification. Also shown is that the magnetism stability can be enhanced to the level at room temperature upon strain, and the massless Dirac-fermion behavior for the β-spin state can be clearly detected in the spin gapless semiconductor phase under appropriate strains.