Christian Binek

Bio: Christian Binek is an academic researcher from University of Nebraska–Lincoln. The author has contributed to research in topics: Magnetization & Exchange bias. The author has an hindex of 26, co-authored 119 publications receiving 4522 citations.

Robust isothermal electric control of exchange bias at room temperature

Abstract: Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with high-speed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr(2)O(3) has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr(2)O(3) single crystal, we achieve reversible, room-temperature isothermal switching of the exchange-bias field between positive and negative values by reversing the electric field while maintaining a permanent magnetic field. This effect reflects the switching of the bulk antiferromagnetic domain state and the interface magnetization coupled to it. The switchable exchange bias sets in exactly at the bulk Neel temperature.

Magnetic nanoparticles: recent advances in synthesis, self-assembly and applications

Abstract: Nanostructured magnetic materials have a variety of promising applications spreading from nano-scale electronic devices, sensors and high-density data storage media to controlled drug delivery and cancer diagnostics/treatment systems. Magnetic nanoparticles offer the most natural and elegant way for fabrication of such (multi-) functional materials. In this review, we briefly summarize the recent progress in the synthesis of magnetic nanoparticles (which now can be done with precise control over the size and surface chemistry), and nanoscale interactions leading to their self-assembly into 1D, 2D or 3D aggregates. Various approaches to self-organization, directed-, or template-assisted assembly of these nanostructures are discussed with the special emphasis on magnetic-field enabled interactions. We also discuss new physical phenomena associated with magnetic coupling between nanoparticles and their interaction with a substrate and the characterization of the physical properties at the nanoscale using various experimental techniques (including scanning quantum interferometry (SQUID) and magnetic force microscopy). Applications of magnetic nanoparticle assemblies in data storage, spintronics, drug delivery, cancer therapy, and prospective applications such as adaptive materials and multifunctional reconfigurable materials are also highlighted.

Magnetoelectric switching of exchange bias.

Abstract: The perpendicular exchange bias field, H(EB), of the magnetoelectric heterostructure Cr2O3(111)/(Co/Pt)(3) changes sign after field cooling to below the Neel temperature of Cr2O3 in either parallel or antiparallel axial magnetic and electric freezing fields. The switching of H(EB) is explained by magnetoelectrically induced antiferromagnetic single domains which extend to the interface, where the direction of their end spins controls the sign of H(EB). Novel applications in magnetoelectronic devices seem possible.

Robust isothermal electric switching of interface magnetization: A route to voltage-controlled spintronics

Abstract: Roughness-insensitive and electrically controllable magnetization at the (0001) surface of antiferromagnetic chromia is observed using magnetometry and spin-resolved photoemission measurements and explained by the interplay of surface termination and magnetic ordering. Further, this surface in placed in proximity with a ferromagnetic Co/Pd multilayer film. Exchange coupling across the interface between chromia and Co/Pd induces an electrically controllable exchange bias in the Co/Pd film, which enables a reversible isothermal (at room temperature) shift of the global magnetic hysteresis loop of the Co/Pd film along the magnetic field axis between negative and positive values. These results reveal the potential of magnetoelectric chromia for spintronic applications requiring non-volatile electric control of magnetization.

Ferroelectric control of magnetism in BaTiO3 /Fe heterostructures via interface strain coupling

Abstract: Reversible control of magnetism is reported for a Fe thin film in proximity of a $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_{3}$ single crystal. Large magnetization changes emerge in response to ferroelectric switching and structural transitions of $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_{3}$ controlled by applied electric fields and temperature, respectively. Interface strain coupling is the primary mechanism altering the induced magnetic anisotropy. As a result, coercivity changes up to 120% occur between the various structural states of $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_{3}$. Up to 20% coercivity change is achieved via electrical control at room temperature. Our all solid state ferroelectric-ferromagnetic heterostructures open viable possibilities for technological applications.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Multiferroic and magnetoelectric materials

Abstract: A ferroelectric crystal exhibits a stable and switchable electrical polarization that is manifested in the form of cooperative atomic displacements. A ferromagnetic crystal exhibits a stable and switchable magnetization that arises through the quantum mechanical phenomenon of exchange. There are very few 'multiferroic' materials that exhibit both of these properties, but the 'magnetoelectric' coupling of magnetic and electrical properties is a more general and widespread phenomenon. Although work in this area can be traced back to pioneering research in the 1950s and 1960s, there has been a recent resurgence of interest driven by long-term technological aspirations.

Physics and Applications of Bismuth Ferrite

Abstract: BiFeO3 is perhaps the only material that is both magnetic and a strong ferroelectric at room temperature. As a result, it has had an impact on the field of multiferroics that is comparable to that of yttrium barium copper oxide (YBCO) on superconductors, with hundreds of publications devoted to it in the past few years. In this Review, we try to summarize both the basic physics and unresolved aspects of BiFeO3 (which are still being discovered with several new phase transitions reported in the past few months) and device applications, which center on spintronics and memory devices that can be addressed both electrically and magnetically.

Multiferroics: progress and prospects in thin films.

Abstract: Multiferroic materials, which show simultaneous ferroelectric and magnetic ordering, exhibit unusual physical properties — and in turn promise new device applications — as a result of the coupling between their dual order parameters. We review recent progress in the growth, characterization and understanding of thin-film multiferroics. The availability of high-quality thin-film multiferroics makes it easier to tailor their properties through epitaxial strain, atomic-level engineering of chemistry and interfacial coupling, and is a prerequisite for their incorporation into practical devices. We discuss novel device paradigms based on magnetoelectric coupling, and outline the key scientific challenges in the field.