Magnetic Multilayer's

Magnetic Multilayer's

Magnetic Multilayer's

INTRODUCTION

A magnetic or multilayer superlattice, consisting of a sequential arrangement of alternating layers of a magnetic material and a non-magnetic with thicknesses in the nanometer scale, within the range of characteristic length of the magnetic interaction between the layers of the superlattice. These heterostructures exhibit new and interesting behavior in their electrical, magnetic and transport properties. The discovery of giant magnetoresistance (GMR) in them opened a wide range of applications, the most important was as magnetic field sensor for use as a read head in hard disk drives and non-volatile magnetic memories (MRAM). Another phenomenon, known as Exchange Bias, exchange or bias, occurs when two materials one ferromagnetic and one antiferromagnetic contact. The interactions of the magnetic moments in the boundary surface or interface when the sample is cooled under the action of a magnetic field at temperatures below the temperature of Niel antiferromagnetic material renders the hysteresis loop is not symmetrical and move to field along the axis of the magnitude [H.sub.E]. An ideal place to study this phenomenon of shifting exchange system is the manganite [La.sub.1-x] [Ca.sub.x] Mn [O.sub.3] (LCMO), which depending on the Ca doping exhibits ferromagnetic and antiferromagnetic phases (Maruyama et.al, 2009).

Nanostructured magnetic systems such as multilayers, nanoparticles and films nanogranulares (dispersions in solid matrices), have been studied in recent years to investigate two physical mechanisms that determine the stability thermal nanomagnets (crucial for increasing the density of magnetic hard disk storage) beyond the obvious influence of size: the interaction between particles (dipolar and / or RKKY in metal matrices) and the anisotropic exchange (exchange-bias) in nanoparticles with core-shell structure (core shell-ferromagnetic or matrizantiferromagnético). complementary manner, this second phenomenon also investigated in geometry of multilayer configuration in which, in fact, find their greatest application (spin valves in readheads ). In particular, groups of Magnetic Materials and UPV UCLM groups include very prominent in the field, have extensive experience in the preparation (by sputtering (sputtering) and recently also with a "source clusters" - cluster gun -) and characterization of the materials described by SQUID magnetometry, X-ray scattering and neutron, and measurement of magnetoresistive properties. Likewise also have extensive experience in the study of magnetic interactions in multilayers of transition metals and rare earth by magnetic measurements, X-ray scattering and neutron reflectometry. Moreover, various groups of the Network also address the study and synthesis of magnetic nanowires arrays multilayer nanostructures are a particularly promising for application in giant magnetoresistance and giant magneto-impedance. 

Today magnetization processes of nanowire arrays are being investigated in order to understand how to control and design their magnetic properties. One of the main advantages of molecular materials (magnetic materials multifunctional molecular character) is its flexibility by chemical methods to optimize a given physical property as well as for the design of materials in which two or more physical properties of interest coexist and may even interact with each other. In a big part of getting these materials increase the magnetic anisotropy of the magnetic centers allow their use in technological applications such as molecular-scale magnetic memory, logical drives ...