Structural studies of magnetic C60/Cu multilayers

J E Shoup,J A Borchers,B J Kirby,D A Arena,C J Kinane,A J Caruana,S Langridge,M Rogers,O Cespedes

doi:10.1063/1.5139229

Abstract

We report on x-ray and neutron scattering studies that reveal the structure of interfaces of C60 layers with adjacent transition metal layers, in this instance, Cu. Such interfaces produce room-temperature long-range spin order that is not described by conventional theories of metallic magnetism. We use a combination of hard x-ray reflectivity and neutron scattering to investigate the interfacial structure of two C60/Cu layered samples: a superlattice with multiple C60/Cu repeats and a simpler tri-layer structure. For both structures, we develop a consistent structural model for the two scattering techniques, which details the critical interfacial roughness between the layers. We find that while x-ray reflectivity provides a strong contrast between the C60 and Cu layers, the similar neutron scattering length density of the two materials severely reduces the neutron scattering contrast. Our results can be used to design material systems that permit studies of the magnetism of the C60/transition metal interfaces with spin-sensitive scattering probes such as polarized neutron reflectometry.

Highlights

Molecular spintronics has a fundamental appeal and offers the promise of practical applications as the incorporation of active organic components into device structures presents an unparalleled variation of device functionality
We find that while x-ray reflectivity provides a strong contrast between the C60 and Cu layers, the similar neutron scattering length density of the two materials severely reduces the neutron scattering contrast
Full field hysteresis loops were measured on both samples, and a half-loop was repeated for the SL sample immediately prior to the neutron scattering measurements [see Fig. 1(a)]

Summary

Introduction

Molecular spintronics has a fundamental appeal and offers the promise of practical applications as the incorporation of active organic components into device structures presents an unparalleled variation of device functionality. The flexibility of physical parameters (e.g., transport properties, luminescence, and chemical sensitivity) afforded by molecular active layers supports development of new device concepts such as spin-sensitive organic light emitting diodes.. With specific regard to spin applications, organic components possess additional desirable properties such as both a large spin diffusion length and long spin lifetime.. With specific regard to spin applications, organic components possess additional desirable properties such as both a large spin diffusion length and long spin lifetime.4,5 These and other characteristics motivate the search for allorganic or hybrid organic/inorganic structures that may form the platform for realizing room-temperature quantum coherent spin manipulation. As in many other organic molecules, electron transport in C60 is primarily via electron hopping, which reduces Eliot–Yafet type spin depolarization.

Methods

Results

Conclusion