Here we present our proposal and initial results on the magnetic field control of plasmon resonances in the mid IR region by the use of the Magneto-Refractive (MR) effect, i.e., a change in the optical properties of the system by magnetic field controlled electrical resistivity. For this we select a Giant Magneto Resistance model system (a Au/Permalloy multilayer), for which changes in resisitivity of the order of 10% by the application of small (of the order of 20 Oe) magnetic fields have been reported. The experiments are carried out in a dedicated magnetic field FTIR (M-FTIR) spectrometer.
In this work we show that the insertion of a dielectric layer in Au/Co/Au magnetoplasmonic nanodisks fabricated by hole
mask colloidal lithography makes it possible to obtain systems that simultaneously exhibit large magneto-optical (MO)
activity and low optical extinction. The physical mechanism underlying this effect is the internal EM field redistribution,
in such a way to concentrate it in the MO active layer (Co) and, at the same time, reduce it in the non MO active
elements. We have performed a systematic study of the optical and MO response upon the variation of the Co layer
thickness within the nanodisk, finding an increase of the MO response with the increment of thickness, accompanied
with a blue shift and broadening of the peaks associated with the plasmon excitations.
We present a structural, magnetic and magneto-optical (MO) study of Co nanoparticles sputter-deposited at different temperatures and embedded in three different matrices (two insulators such as MgO and AlN and a metal such as Pt). MgO capping layer does not affect the magnetism of the nanoparticles as demonstrated by in situ transversal and ex situ polar Kerr loops. The structure of the nanoparticles was investigated by TEM and a Co crystalline core surrounded by an amorphous crust was observed. From the analysis of the MO spectral response of the nanoparticles we demonstrate that the evolution of the MO constants as a function of Co concentration can be explained with the Maxwell-Garnett model. It is also observed that the reduction of nanoparticles size gives rise to a decrease of the relaxation time of the electrons into them. The deposition of Pt capping gives rise to the magnetic connection of the islands mediated by the polarised Pt, with the formation of different Co-Pt compounds as was observed with TEM. We observe that in the case of AlN capping destroys the magnetism of the samples due to a strong nitridation of Co.
MBE is a powerful synthesis technique for preparation of ordered intermetallic phases since the high rates of surface diffusion allow in-plane chemical ordering to occur at temperatures far below those which are necessary for ordering in bulk samples. This lifting of kinetic constraints enables the phase diagrams to be explored at low temperatures where bulk ordering processes are often too sluggish for phase equilibria to be reached. Specifically, we describe the preparation of epitaxial films (in the thickness range 100 - 1000 angstrom) of ordered intermetallic phases in the Co-Pt and Fe-Pt intermetallic systems. Such phases are of potential importance for magnetic and magneto-optical storage applications. In particular we discuss growth and chemical ordering in epitaxial Co1-xPtx films near x equals 0.25, 0.5, and 0.75 as well as Fe1-xPtx films near x equals 0.5. Depending on growth conditions these phases order spontaneously during growth with resulting changes in the Kerr spectra. Ordering results in large Kerr rotations (approximately 1 degree(s)) in the UV spectral region for the films with x near 0.5.
Conference Committee Involvement (2)
Nanotechnology II
9 May 2005 | Sevilla, Spain
Nanotechnology
19 May 2003 | Maspalomas, Gran Canaria, Canary Islands, Spain
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.