Additive Effects during Pulsed Deposition of Cu-Co Nanostructures

Abstract

Electrodeposited alloys showing useful magnetic properties have been the focus of much study due to their technological importance for data storage and retrieval. [1][2][3][4][5][6] Most investigators studied the effects of processing conditions, such as deposition rate, pH, temperature, and mixing conditions, particularly for the Ni-Fe system. [7][8][9] Recent work has examined the giant magnetoresistances (GMR) for various combinations of electrodeposited multilayered magnetic alloys, primarily for reading and sensor applications. 10-13 Besides these multilayered alloys, there are other types of magnetic composite materials that could be used to create interesting magnetic devices, for instance, "granular" materials (magnetic clusters embedded in a nonmagnetic matrix) and hybrid cluster/multilayer alloys. 14-18 Multilayered nanowires produced with templates have attracted much attention as well. [19][20][21] Pulsed electrodeposition is well suited to the production of multilayer alloys. 22,23 We discuss the possibility of extending this technique to create novel Cu/Co composite structures with an electrolyte similar to one recently considered in the literature 24 using no template or masking technique. The microstructural effects of pulse parameters and two additives in this electrolyte, saccharin and sodium dodecyl sulfate (SDS), are investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM); the current efficiency, surface roughness, and composition are measured also. Other studies of electrodeposited Cu-Co alloys are available, 10,11,13,17,[25][26][27] in one of which the effects of two leveling agents on the electrodeposits are discussed. 26 Practically, additives are of industrial interest since some have been shown to improve the properties of magnetic write-head materials that are increasingly subject to new performance requirements. 9,24,28-30 A fundamental interest exists as well, since little is known about how additives effect changes in these material properties. [31][32][33] Experimental Films for microstructural and compositional analysis were deposited using an inverted rotating disk electrode (RDE), described in detail elsewhere. 34,35 Substrates for subsequent microstructural analysis were 100 nm of (111) preferentially oriented Ag sputtered on the polished side of doped Si disks having Ti adhesion layers; more details on these substrates are available elsewhere. 36 For compositional analysis, bulk Ag (99.95%, Goodfellow, England) working electrodes (WEs) polished to a near mirror finish and ultrasonically cleaned with ethanol served as substrates. The WE exposed area was 0.50 cm 2 for both types of substrates. A Labview program controlled a Heka potentiostat (PG 390 Heka Elektronik GmbH, Germany) for pulsed deposition. A mercury/mercurous sulfate electrode (Radiometer, France) acted as the reference electrode, while a dimensionally stable anode (Eltech Systems Corp.) served as the counter electrode. The rotation speed for all experiments was 1000 rpm. Depo...

Electrodeposition on Ni from a Sulfamate Electrolyte Part 1: Effect of a Stress Relief on Annealing Behavior and Film Metallurgy

“…Saccharin is well known as a grain-refining agent that reduces stress in the deposited films, in some cases eliminating the columnar morphology associated with the electrodeposited iron group metals altogether. 20 The effect in Figure 3 is consistent with previous work in that the grain structure of the Ni film deposited with saccharin is refined to the point where it is not easily observable via SEM. Arrows in the micrograph show the clear grain boundary.…”

In situ magnetization measurements of Cu/Co multilayers during the process of electrodeposition

“…This phenomenon has been shown to occur for Cu-Co and Cu-Ni layers pulse plated in galvanostatic conditions. 7,8 In our case we applied potential pulses, so the displacement is probably less important than in galvanostatic conditions. As shown in Fig.…”

Nanostructured Materials Synthesized Using Electrochemical Techniques

“…With regards to the Cu-Co multilayers nanostructures, Kelly et al [265,266] have clearly shown that sodium dodecyl sulfate promotes the displacement reaction of Co by Cu 2þ during pulse off-times. Gundel et al [267] assumed that the displacement reaction could be negligible under galvanostatic conditions.…”