Search

Emergent phenomena such as two-dimensional electron gas (2DEG) and interfacial superconductivity and ferromagnetism are generally built on the interface between insulating oxide thin films and substrates, e.g., LaAlO3/SrTiO3, where the 2D profiles of these electronic states are precisely confined at the interface of two insulators. Herein we report a high-mobility electron gas state with unusual symmetry at the interface of the Sr2CrMoO6/SrTiO3 (110) heterostructures, the fermiology of which follows the cubic crystallographic symmetry rather than the two-dimensional interface itself, resulting in the identical Shubnikov-de Haas oscillations with applied magnetic field along all the twelve equivalent [110] crystallographic directions of SrTiO3, distinctly different from the 2D nature of the electron gas reported previously. Neutron diffraction verifies the predicted ferrimagnetic ordering between Cr and Mo moments. This, together with the magnetic hysteresis loops and negative magnetoresistance in low-field region, suggests possible spin polarization of itinerant electrons. Therefore, a quasi-3D profile, high mobility (up to 104 cm2 V−1 s−1) and possibly spin polarized electronic state is observed in the double-perovskite-based oxide heterostructures. This finding of the electronic properties in Sr2CrMoO6/SrTiO3 (110) heterostructure expands the knowledge of interfacial physics, as well as shines light on oxide-based electronics and spintronics research. The existence of electron gas at the interfaces of oxide-based heterostructures with broken spatial inversion symmetry gives rise to various interesting physical phenomena. Here, the authors report a new type quasi-three-dimensional electron gas state at the interface of ferrimagnetic semiconductor-strontium titanate heterostructures, which show high mobility, high valley degeneracy and possible spin polarization. [ABSTRACT FROM AUTHOR]

The antichiral edge states induced by the modified Haldane model have been predicted in the previous studies. In this study, other types of antichiral edge states are proposed by applying the side potentials composed of a potential field, staggered electric field, and exchange field along the boundaries of zigzag honeycomb nanoribbons (zHNRs). Their corresponding transport properties are investigated. The results show that the side potentials can lift the spin degeneracy of the edge modes, inducing five types of antichiral edge states. By calculating the spin-dependent energies in K' and K valleys of the edge modes, an interpretation for generating antichiral edge states is proposed. In addition, the spin/charge switcher in the three-terminal device consisting of zHNRs is developed based on the induced edge states. We believe that these results can be used in the design of future spintronic devices. In the modified Haldane model, antichiral edge states appear at the boundary of zigzag honeycomb nanoribbons. These flow oppositely at the boundary and the center of the ribbon. In this work, the authors show how to decorate the system boundary to control the edge modes' current and spin polarization. They show how to form a three-terminal system where an unpolarized current splits into two fully spin-polarized ones. [ABSTRACT FROM AUTHOR]

Sustaining exotic quantum mechanical phases at high temperatures is a long-standing goal of condensed matter physics. Among them, half-metals are spin-polarized conductors that are essential for realizing room-temperature spin current sources. However, typical half-metals are low-temperature phases whose spin polarization rapidly deteriorates with temperature increase. Here, we first show that a low-temperature insulator with an unequal charge gap for the two spin channels can arise from competing Mott and band insulating tendencies. We establish that thermal fluctuations can drive this insulator to a half-metal through a first-order phase transition by closing the charge gap for one spin channel. This half-metal has 100% spin polarization at the onset temperature of metallization. Further, varying the strength of electron repulsion can enhance the onset temperature while preserving spin polarization. We outline experimental scenarios for realizing this tunable finite temperature half-metal. Maintaining full spin polarization in half-metallic materials with temperature increase has remained a longstanding challenge for engineering room-temperature spintronics applications. Here, the authors theoretically propose a way to achieve half-metallicity with complete spin polarization at high temperatures by tuning thermal fluctuations, electron correlation, and charge transfer effects in a low-temperature Mott insulator. [ABSTRACT FROM AUTHOR]

Optical pumping is an efficient method for initializing and maintaining atomic spin ensembles in a well-defined quantum spin state. Standard optical pumping methods orient the spins by transferring photonic angular momentum to spin polarization. Generally the spins are oriented along the propagation direction of the light due to selection rules of the dipole interaction. Here we present and experimentally demonstrate that by modulating the light polarization, angular momentum perpendicular to the optical axis can be transferred efficiently to cesium vapor. The transverse pumping scheme employs transversely oriented dark states, allowing for control of the trajectory of the spins on the Bloch sphere. This new mechanism is suitable and potentially beneficial for diverse applications, particularly in quantum metrology. The ability to orient atomic spins via optical pumping has important implications for the fields of quantum information and metrology, and while polarization typically occurs parallel to the optical axis, it is often desirable to orient spins along a transverse magnetic field. This work demonstrates an optical pumping scheme for transverse orientation of the spin of cesium vapor, allowing control of spin trajectories. [ABSTRACT FROM AUTHOR]

Spin-transfer torque nano-oscillators (STNO) are important candidates for several applications based on ultra-tunable microwave generation and detection. The microwave dynamics in these STNOs are induced by spin currents that are typically generated either by spin polarization in an adjacent ferromagnetic layer or through the spin Hall effect. In this paper, a 3-terminal STNO based on a magnetic tunnel junction is excited by both of these spin injection mechanisms. The combination of these two mechanisms excites the free layer into dynamic regimes beyond what can be achieved by each excitation mechanism individually, resulting in enhanced output powers, a key figures of merit for device performance. The system response can be coherently quantified as a function of the total injected spin current density. The experimental data shows an excellent consistency with this simple model and a critical spin current density of 4.52 ± 0.18 × 109ħ/2 e−1 Am−2. Spin torque nano-oscillators are important candidates for several device applications. The authors demonstrate that the combination of two excitation methods, spin-polarised tunnelling current and pure spin Hall current, allows them to achieve greater injected spin current densities and power output than by each individual mechanism. [ABSTRACT FROM AUTHOR]

The discovery and realization of graphene as an ideal two-dimensional (2D) material has triggered extensive efforts to create similar 2D materials with exciting spin-dependent properties. Here, we report on a novel Sn 2D superstructure on Au(111) that shows similarities and differences to the expected electronic features of ideal stanene. Using spin- and angle-resolved photoemission spectroscopy, we find that a particular Sn/Au superstructure reveals a linearly dispersing band centered at the Γ ¯ -point and below the Fermi level with anti-parallel spin polarization and a Fermi velocity of vF ≈ 1×106 m/s, the same value as for graphene. We attribute the origin of the band structure to the hybridization between the Sn and the Au orbitals at the 2D Sn-Au interface. Considering that free-standing stanene simply cannot exist, our investigated structure is an important step towards the search of useful stanene-like overstructures for future technological applications. The successful isolation of a single layer of graphene has led to great interest in finding other 2D materials with similar electronic characteristics with additional spin-dependent phenomena. In this work, a 2D allotrope of Sn is grown on an Au(111) surface and shown through angle-resolved photoemission spectroscopy to have a linear band dispersion at the zone center and anti-parallel spin polarization. [ABSTRACT FROM AUTHOR]