Chuangye Song

Bio: Chuangye Song is an academic researcher from Beijing Normal University. The author has contributed to research in topics: Materials science & Scanning tunneling microscope. The author has an hindex of 7, co-authored 16 publications receiving 311 citations. Previous affiliations of Chuangye Song include Chinese Academy of Sciences.

Giant piezoelectric d33 coefficient in ferroelectric vanadium doped ZnO films

Abstract: A giant electromechanical d33 coefficient 110pC∕N is obtained in ferroelectric V-doped ZnO films, which is nearly one order of magnitude higher than that of undoped samples. It is considered that the switchable spontaneous polarization induced by V dopants and the accompanying relatively high permittivity should be responsible for the enhancement of piezoelectric response. Moreover, from another point of view, an easier rotation of V–O bonds which are noncollinear with c axis under electric field might be the microscopic origin of this anomaly. The improved piezoelectric properties could make V-doped ZnO a promising candidate for piezoelectric devices.

Defect-Engineered Dzyaloshinskii-Moriya Interaction and Electric-Field-Switchable Topological Spin Texture in SrRuO3.

Abstract: In situ electrical control of the Dzyaloshinskii-Moriya interaction (DMI) is one of the central but challenging goals toward skyrmion-based device applications. An atomic design of defective interfaces in spin-orbit-coupled transition-metal oxides can be an appealing strategy to achieve this goal. In this work, by utilizing the distinct formation energies and diffusion barriers of oxygen vacancies at SrRuO3 /SrTiO3 (001), a sharp interface is constructed between oxygen-deficient and stoichiometric SrRuO3 . This interfacial inversion-symmetry breaking leads to a sizable DMI, which can induce skyrmionic magnetic bubbles and the topological Hall effect in a more than 10 unit-cell-thick SrRuO3 . This topological spin texture can be reversibly manipulated through the migration of oxygen vacancies under electric gating. In particular, the topological Hall signal can be deterministically switched ON and OFF. This result implies that the defect-engineered topological spin textures may offer an alternate perspective for future skyrmion-based memristor and synaptic devices.

Room temperature ferromagnetism and ferroelectricity in cobalt-doped LiNbO3 film

Abstract: (5at.%) cobalt-doped LiNbO3 (Co:LN) films were prepared by combinatorial laser molecular-beam epitaxy on Si (100). The Co:LN films with Co2+ replacing Nb exhibit room temperature ferromagnetism of 1.2μB∕Co and Curie temperature of ∼540K. Through a Ag∕Co:LN∕Si metal-ferroelectric-semiconductor field effect transistor configuration, ferroelectric measurements show that the films display hysteresis loops at 300K and ferroelectric transition temperature of ∼610K. The hysteresis and the asymmetry in capacitance-voltage and leakage-voltage curves are ascribed to trapping/detrapping process of charges at the Co:LN/Si interface. The coexistence of room temperature ferromagnetism and ferroelectricity makes Co:LN a promising single-phase multiferroic.

Tuning the training effect in exchange biased NiO/Ni bilayers

Abstract: Exchange bias is reduced upon magnetic field cycling, which is referred to as the training effect. Here, large fields of 10kOe, both out of plane and in plane, are applied to tune the training effect in exchange biased NiO∕Ni bilayers. It is found that the large fields, especially for the out-of-plane field, accelerate the training effect, i.e., the exchange bias field decreases abruptly, while the coercivity increases at first and then decreases. These phenomena could be caused by field induced changes in the NiO domain structure, which is supported by measurements of consecutive hysteresis loops with increasing fields.

Ferromagnetism and possible application in spintronics of transition-metal-doped ZnO films

Abstract: This review article first presents a summary of current understanding of the magnetic properties and intrinsic ferromagnetism of transition-metal (TM)-doped ZnO films, which are typical diluted magnetic oxides used in spintronics. The local structure and magnetic behavior of TM-doped ZnO are strongly sensitive to the preparation parameters. In the second part, we discuss in detail the effects of doping elements and concentrations, oxygen partial pressure, substrate and its orientation and temperature, deposition rate, post-annealing temperature and co-doping on the local structure and subsequent ferromagnetic ordering of TM-doped ZnO. It is unambiguously demonstrated that room-temperature ferromagnetism is strongly correlated with structural defects, and the carriers involved in carrier-mediated exchange are by-products of defects created in ZnO. The third part focuses on recent progress in TM-doped ZnO-based spintronics, such as magnetic tunnel junctions and spin field-effect transistors, which provide a route for spin injection from TM-doped ZnO to ZnO. Thus, TM-doped ZnO materials are useful spin sources for spintronics.

Exchange bias effect in alloys and compounds

Abstract: The phenomenology of exchange bias effects observed in structurally single-phase alloys and compounds but composed of a variety of coexisting magnetic phases such as ferromagnetic, antiferromagnetic, ferrimagnetic, spin-glass, cluster-glass and disordered magnetic states are reviewed. The investigations on exchange bias effects are discussed in diverse types of alloys and compounds where qualitative and quantitative aspects of magnetism are focused based on macroscopic experimental tools such as magnetization and magnetoresistance measurements. Here, we focus on improvement of fundamental issues of the exchange bias effects rather than on their technological importance.

Influence of nitrogen and phosphorous on the growth and root morphology of Acer mono.

Abstract: Nitrogen and phosphorous are critical determinants of plant growth and productivity, and both plant growth and root morphology are important parameters for evaluating the effects of supplied nutrients. Previous work has shown that the growth of Acer mono seedlings is retarded under nursery conditions; we applied different levels of N (0, 5, 10, and 15 g plant-1) and P (0, 4, 6 and 8 g plant-1) fertilizer to investigate the effects of fertilization on the growth and root morphology of four-year-old seedlings in the field. Our results indicated that both N and P application significantly affected plant height, root collar diameter, chlorophyll content, and root morphology. Among the nutrient levels, 10 g N and 8 g P were found to yield maximum growth, and the maximum values of plant height, root collar diameter, chlorophyll content, and root morphology were obtained when 10 g N and 8 g P were used together. Therefore, the present study demonstrates that optimum levels of N and P can be used to improve seedling health and growth during the nursery period.

Exchange bias in ferromagnet/antiferromagnet bilayers

Abstract: Since the exchange bias (EB) effect was discovered in the Co/CoO core-shell nanoparticles, it has been extensively studied in various ferromagnet (FM)/antiferromagnet (AFM) bilayers due to its crucial role in spintronics devices. In this article, we review the investigation of the EB in our research group. First, we outline basic features of the EB, including the effects of the constituent layer thickness, the microstructure and magnetization of the FM layers, and we also discuss asymmetric magnetization reversal process in wedged-FM/AFM bilayers. Secondly, we discuss the mechanisms of the positive EB and the perpendicular EB. Thirdly, we demonstrate the hysteretic behavior of the angular dependence of the EB and analyze the EB training effect. Finally, we discuss the roles of the rotatable anisotropy in the two phenomena.