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We investigate the individual and combined effects of substitutional Mn-doping and strain engineering in monolayers of MoS2 and MoSe2, using density functional theory (DFT) to examine the structural, electronic, and magnetic properties. Doping with Mn is shown to introduce magnetic character by producing localized spin polarization in the region near the defect. The Mn dopants preferentially couple ferromagnetically due to an interaction that is described as double exchange. Additionally, doping with Mn changes the electronic structure by introducing defect states within the band gap, which according to one form of DFT, results in half-metallic character. Compressive and tensile strain both decrease the band gap in the pure transition metal dichalcogenides (TMDs), retaining the materials' semiconducting character. Strain has a multi-varied effect on the electronic properties in the Mn-doped TMDs. Tensile strain demonstrates potential to strengthen ferromagnetic coupling, offering new possibilities for strain-engineering dilute magnetic semiconductors with more enhanced stability at room temperature. [ABSTRACT FROM AUTHOR]

Three different contributing mechanisms have been considered to calculate the magnetization (M) of p-type Pb1-xMnxSe for a hole density of p = 5 × 1018 cm−3and n-type Pb1-xMnxS for an electron density of n = 6 × 1018 cm−3.The first mechanism comes from the valence band diamagnetism which is calculated in a frame of the two-band model. The second mechanism which we consider arises from the spin densities of holes and electrons and we use a six-level k →. π → theory in second-order perturbation theory in the effective mass representation. The third mechanism is the impurity Mn+2 ions contribution, and we consider small clusters consisting of one, two and three spins to evaluate it. The three spin clusters include both open and closed types. It has been observed that the former two mechanisms contribute very little to the magnetization compared to the latter one. However, their importance cannot be ignored because they provide a deeper understanding of the underlying physical mechanisms involved with carrier spin polarization and orbital diamagnetism of the host matrix, in which the Mn+2 spins are embedded. Good agreement of our theory with experiment is the other interesting and distinct feature of this work. [ABSTRACT FROM AUTHOR]

Abstract The electronic structures and magnetic properties of 6H-SiC doped with N, C vacancies (V C), Si vacancies (V Si) and Al are studied by first principles calculations. The results indicate that the N substituting C in 6H-SiC cannot order magnetism but V Si can introduce magnetic moments effectively. Ferromagnetism coupling is obtained in (N, 2 V Si)-codoped 6H-SiC. The ferromagnetism can be mainly attributed to the interactions between the 2 p orbitals of C atoms around Si vacancies. More interestingly, substituting Si with Al can enhance the ferromagnetic states in 6H-SiC in neutral states. We also studied the effect of charge on magnetic properties and provide an effective method of tuning magnetism in 6H-SiC. Highlights • The doping with N Si , V Si and (N C , V Si) can induce ferromagnetism in 6H-SiC crystal. • Ferromagnetism can be enhanced by Al substituting and charge. • The spin polarization is proposed as the origin of ferromagnetism. [ABSTRACT FROM AUTHOR]

We propose a coaxial cylindrical quantum well wire which is composed of layers of a dilute magnetic semiconductor (DMS) and a nonmagnetic semiconductor (NMS). Using effective mass approximation, we present a numerical calculation of the eigenenergies and eigenstates of electrons in the heterostructure. The variation of the spin‐dependent energy levels is influenced by the giant Zeeman splitting and potential energies due to a vector potential for sufficiently low and high magnetic fields, respectively. It is found that crossing and anticrossing behaviors of energy levels can be controlled by the thickness of a NMS layer. The ballistic transport of the structure is also investigated. The ranges of the Fermi energy for obtaining full spin polarization are suggested in this work. [ABSTRACT FROM AUTHOR]

• BaNi x Nb (1-x) O 3-δ has strong RTFM (M sat ∼2.54 emu/g, M r ∼0.228 emu/g, and H c ∼99.14Oe). • Cubic to tetragonal phase transition due to Ni2+ doping is the key to strong RTFM. • Ni doping balances oxygen vacancy and leads to a valence state mixing of Nb. Here, we report a strong room-temperature magnetism in Ni-doped BaNbO 3. The tetragonal BaNi x Nb (1-x) O 3-δ nano-powders are prepared by the composite-hydroxide-mediated method. The as-prepared BaNi x Nb (1-x) O 3-δ has a saturation magnetization (M sat) of 2.54 emu/g, a remnant magnetization (M r) of 0.228 emu/g, and a small coercive field (Hc) of 99.14 Oe at room temperature, presenting as a short-range magnetic order. The Ni-doping leads to an incommensurate valence state of Nb, and the oxidation state of Ni in the matrix is + 2. It brings not only strong local spin polarization to the matrix, but also balances the oxygen defects and gives rise to a more doping content. The strong magnetism originated from the existence of short-range magnetic order and the strong local net spin polarization at the Fermi level (E F), which are proved by the first-principle calculations. [ABSTRACT FROM AUTHOR]

We study the magnetization and the magnetic phases of II-VI-based n-doped nonmagnetic- semiconductor (NMS) / narrow to wide dilute-magnetic-semiconductor (DMS) / n-doped NMS quantum wells under in-plane magnetic field. The parallel magnetic field is used as a tool, in order to achieve non-step-like density of states in these -appropriate for conduction-band spintronics- structures. [ABSTRACT FROM AUTHOR]

Abstract: Due to the competition between spatial and magnetic confinement, the density of states (DOS) of a quasi-two-dimensional system deviates from the ideal step-like form both quantitatively and qualitatively. We study how this affects the spin-subband populations and the spin polarization as functions of the temperature, T, and the in-plane magnetic field, B, for narrow to wide dilute-magnetic-semiconductor quantum wells (QWs). We focus on the QW width, the magnitude of the spin–spin exchange interaction, and the sheet carrier concentration dependence. We look for ranges where the system is completely spin polarized. Increasing T, the carrier spin splitting, , decreases, while on increasing B, increases. Moreover, due to the DOS modification, all energetically higher subbands become gradually depopulated. [Copyright &y& Elsevier]