Zhicheng Zhong

Bio: Zhicheng Zhong is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Condensed matter physics & Physics. The author has an hindex of 33, co-authored 98 publications receiving 3212 citations. Previous affiliations of Zhicheng Zhong include Vienna University of Technology & MESA+ Institute for Nanotechnology.

Controlled lateral anisotropy in correlated manganite heterostructures by interface-engineered oxygen octahedral coupling

Abstract: Controlled in-plane rotation of the magnetic easy axis in manganite heterostructures by tailoring the interface oxygen network could allow the development of correlated oxide-based magnetic tunnelling junctions with non-collinear magnetization, with possible practical applications as miniaturized high-switching-speed magnetic random access memory (MRAM) devices. Here, we demonstrate how to manipulate magnetic and electronic anisotropic properties in manganite heterostructures by engineering the oxygen network on the unit-cell level. The strong oxygen octahedral coupling is found to transfer the octahedral rotation, present in the NdGaO3 (NGO) substrate, to the La2/3Sr1/3MnO3 (LSMO) film in the interface region. This causes an unexpected realignment of the magnetic easy axis along the short axis of the LSMO unit cell as well as the presence of a giant anisotropic transport in these ultrathin LSMO films. As a result we possess control of the lateral magnetic and electronic anisotropies by atomic-scale design of the oxygen octahedral rotation

Stacking tunable interlayer magnetism in bilayer CrI 3

Abstract: Interlayer magnetic interactions between two-dimension van der Waals layers are often thought to be weak or even negligible and their mechanism is largely unexplored. Here, the authors propose a mechanism for these interactions in a CrI${}_{3}$ bilayer, based on the concept of covalent-like quasibonding, which offers significant alteration of interlayer wave-function hybridization but small energetic difference between different stacking configurations. While a near-collinear coupling between two parallel spin-polarized I 5$p$ orbitals prefers interlayer ferromagnetism, a noncollinear one favors antiferromagnetism, which is tunable by surmounting a tiny energy barrier between two stacking orders. This explains experimental observations and suggests a strategy for designing interlayer magnetism.

Theory of spin-orbit coupling at LaAlO 3 /SrTiO 3 interfaces and SrTiO 3 surfaces

Abstract: The theoretical understanding of the spin-orbit coupling (SOC) effects at LaAlO${}_{3}$/SrTiO${}_{3}$ interfaces and SrTiO${}_{3}$ surfaces is still in its infancy. We perform first-principles density-functional-theory calculations and derive from these a simple tight-binding Hamiltonian, through a Wannier function projection and group theoretical analysis. We find striking differences to the standard Rashba theory for spin-orbit coupling in semiconductor heterostructures due to multiorbital effects: By far the biggest SOC effect is at the crossing point of the $xy$ and $yz$ (or $zx$) orbitals, and around the $\ensuremath{\Gamma}$ point a Rashba spin splitting with a cubic dependence on the wave vector $\stackrel{P\vec}{k}$ is possible.

Theory of spin-orbit coupling at LaAlO3/SrTiO3 interfaces and SrTiO3 surfaces

Abstract: The theoretical understanding of the spin-orbit coupling (SOC) effects at LaAlO3/SrTiO3 interfaces and SrTiO3 surfaces is still in its infancy. We perform first-principles density-functional-theory calculations and derive from these a simple tight-binding Hamiltonian, through a Wannier function projection and group theoretical analysis. We find striking differences to the standard Rashba theory for spin-orbit coupling in semiconductor heterostructures due to multiorbital effects: By far the biggest SOC effect is at the crossing point of the xy and yz (or zx) orbitals, and around the point a Rashba spin splitting with a cubic dependence on the wave vector k is possible.

Spin Direction-Controlled Electronic Band Structure in Two-Dimensional Ferromagnetic CrI3.

Abstract: Manipulating physical properties using the spin degree of freedom constitutes a major part of modern condensed matter physics and is a key aspect for spintronics devices. Using the newly discovered two-dimensional van der Waals ferromagnetic CrI3 as a prototype material, we theoretically demonstrated a giant magneto band-structure (GMB) effect whereby a change of magnetization direction significantly modifies the electronic band structure. Our density functional theory calculations and model analysis reveal that rotating the magnetic moment of CrI3 from out-of-plane to in-plane causes a direct-to-indirect bandgap transition, inducing a magnetic field controlled photoluminescence. Moreover, our results show a significant change of Fermi surface with different magnetization directions, giving rise to giant anisotropic magnetoresistance. Additionally, the spin reorientation is found to modify the topological states. Given that a variety of properties are determined by band structures, our predicted GMB effec...

Field-effect tunneling transistor based on vertical graphene heterostructures.

Abstract: An obstacle to the use of graphene as an alternative to silicon electronics has been the absence of an energy gap between its conduction and valence bands, which makes it difficult to achieve low power dissipation in the OFF state We report a bipolar field-effect transistor that exploits the low density of states in graphene and its one-atomic-layer thickness Our prototype devices are graphene heterostructures with atomically thin boron nitride or molybdenum disulfide acting as a vertical transport barrier They exhibit room-temperature switching ratios of ≈50 and ≈10,000, respectively Such devices have potential for high-frequency operation and large-scale integration