A. Friederich

Bio: A. Friederich is an academic researcher from University of Paris-Sud. The author has contributed to research in topics: Capacitance & Capacitor. The author has an hindex of 8, co-authored 15 publications receiving 7712 citations.

Giant magnetoresistance of (001)Fe/(001)Cr magnetic superlattices.

Abstract: We have studied the magnetoresistance of (001)Fe/(001)Cr superlattices prepared by molecularbeam epitaxy. A huge magnetoresistance is found in superlattices with thin Cr layers: For example, with ${t}_{\mathrm{Cr}}=9$ \AA{}, at $T=4.2$ K, the resistivity is lowered by almost a factor of 2 in a magnetic field of 2 T. We ascribe this giant magnetoresistance to spin-dependent transmission of the conduction electrons between Fe layers through Cr layers.

A comparative study of the molecular‐beam epitaxial growth of Ag/Fe, Ag/Cr, and Fe/Cr superlattices on GaAs (001)

Abstract: Ag/Fe, Ag/Cr, and Fe/Cr superlattices grown on GaAs (001) by molecular‐beam epitaxy are compared on the basis of their structural properties. Highly ordered superlattices with very sharp interfaces are obtained for Ag‐based structures (Ag/Fe, Ag/Cr). Although several attempts have been made to improve the growth process of Fe/Cr superlattices, they are far from being so well defined. This is a consequence of a progressive degradation which occurs when the superlattice thickness increases and becomes clearly observable in reflection high‐energy electron diffraction above roughly 300 A. However, using an optimum growth temperature, reasonably well‐defined structures, suitable for subsequent magnetic studies, are obtained.

Molecular beam epitaxial growth of Fe/Cr multilayers on (001)GaAs

Abstract: Molecular beam epitaxy has been used to grow single‐crystal Fe/Cr magnetic multilayer structures on homoepitaxial (001)GaAs layers. The epitaxial relationships between Fe, Cr, and GaAs were determined by in situ reflection high‐energy electron diffraction. The sharpness of the different interfaces of the Fe/Cr multilayers is illustrated by Auger electron spectroscopy sputter depth profiling, which shows that no significant intermixing occurs in the investigated growth temperature range −50 to +50 °C.

MAGNETIC PROPERTIES OF (001)Fe/(001)Cr bcc MULTILAYERS

Abstract: Mesures d'aimantation, de couple magnetique et de magnetoresistance sur des couches multiples Fe(001)/Cr(001) preparees par epitaxie par faisceau moleculaire. On observe des couplages antiferromagnetiques intercouche et une magnetoresistance elevee

Giant Magnetoresistance of (001) Fe / (001) Cr Superlattices

Abstract: We recently reported the observation of a very large magnetoresistance in (001)Fe/(001)Cr superlattices grown by MBE. The magnetoresistance is found to be very large for thin Cr layers. We ascribe this magnetoresistance to a magnetic gate effect. We recently reported the observation of a very large magnetoresistance in (001)Fe/(001)Cr superlattices with thin Cr layers [1]. A large magnetoresitance has also been observed in Fe/Cr/Fe sandwhiches [2]. In both cases, for Cr layers thinner than about 30 A an antiparallel coupling of the magnetization of neighbor Fe layers is indicated by magnetic, magneto-optic and light scattering measurements [1–3]. It thus turns out that the large magnetoresistance os associated with the change to parallel alignment in an applied field. In this paper, we present new data on the magnetic and transport properties of Fe/Cr superlattics and we concentrate on the discussion of the microscopic origin of the magnetoresistance

Spintronics: a spin-based electronics vision for the future.

Abstract: This review describes a new paradigm of electronics based on the spin degree of freedom of the electron. Either adding the spin degree of freedom to conventional charge-based electronic devices or using the spin alone has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices. To successfully incorporate spins into existing semiconductor technology, one has to resolve technical issues such as efficient injection, transport, control and manipulation, and detection of spin polarization as well as spin-polarized currents. Recent advances in new materials engineering hold the promise of realizing spintronic devices in the near future. We review the current state of the spin-based devices, efforts in new materials fabrication, issues in spin transport, and optical spin manipulation.

Spintronics: Fundamentals and applications

Abstract: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.

Thousandfold Change in Resistivity in Magnetoresistive La-Ca-Mn-O Films

Abstract: A negative isotropic magnetoresistance effect more than three orders of magnitude larger than the typical giant magnetoresistance of some superlattice films has been observed in thin oxide films of perovskite-like La0.67Ca0.33MnOx. Epitaxial films that are grown on LaAIO3 substrates by laser ablation and suitably heat treated exhibit magnetoresistance values as high as 127,000 percent near 77 kelvin and ∼1300 percent near room temperature. Such a phenomenon could be useful for various magnetic and electric device applications if the observed effects of material processing are optimized. Possible mechanisms for the observed effect are discussed.

Why Are There so Few Magnetic Ferroelectrics

Abstract: Multiferroic magnetoelectrics are materials that are both ferromagnetic and ferroelectric in the same phase. As a result, they have a spontaneous magnetization that can be switched by an applied magnetic field, a spontaneous polarization that can be switched by an applied electric field, and often some coupling between the two. Very few exist in nature or have been synthesized in the laboratory. In this paper, we explore the fundamental physics behind the scarcity of ferromagnetic ferroelectric coexistence. In addition, we examine the properties of some known magnetically ordered ferroelectric materials. We find that, in general, the transition metal d electrons, which are essential for magnetism, reduce the tendency for off-center ferroelectric distortion. Consequently, an additional electronic or structural driving force must be present for ferromagnetism and ferroelectricity to occur simultaneously.

Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

Abstract: We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.