No abstract

With the decreasing size of devices, the ability to organize materials and control their physical properties through spatial and morphology manipulation becomes critical. Here, we show that the nature of the organic functional group at the top surface of the self-assembled monolayers can strongly influence the growth of a metallic thin film on the monolayer, as a chemical reaction may occur at the interface. We have sputtered Permalloy (Ni79Fe21) on patterned templates of polar and nonpolar self-assembled monolayers. Uniform film formation is observed on polar regions, and cluster/dropletlike structures are formed on the nonpolar regions. A similar behavior in morphology is observed for the deposition of Permalloy on a substrate having single component self-assembled monolayers. Magnetic measurements reveal that Permalloy exhibits a superparamagnetic behavior when deposited on a nonpolar self-assembled monolayer substrate, whereas a ferromagnetic behavior is observed for Permalloy deposited on a polar self-assembled monolayer substrate. Thus, a systematic deposition of Permalloy on polar and nonpolar self-assembled monolayers allows a control on morphology and the magnetic properties due to the difference in wettability of the terminal organic functional groups of the self-assembled monolayers.

A number of Gd based compounds have been investigated for their potential for use in hyperthermia treatment of cancer. The use of magnetic nanoparticles for producing local heating via alternating magnetic fields in cancer affected areas of the body has been an object of numerous studies in recent years. Whereas most studies have focused on using Fe and Co based nanoparticles, we have investigated a number of Gd compounds and alloys for their possible applications in hyperthermia treatment of cancer. Our results suggest that several of these alloys exhibit desired properties for such applications and may have advantages over Fe and Co based alloys for such applications.

Structural and magnetic properties have been studied across the Gd5(Si1−xGex)4 and (Gd1−xRx)5Si4 series, with R=Ce Nd, Er, and Ho, in the context of their use as ferromagnetic materials in the self-controlled hyperthermia treatment of cancer. The study shows that these materials have high magnetization values and their magnetic ordering temperatures (TC) can be varied linearly over a broad range by adjusting the composition of the constituent elements. The magnetization values of these materials are close to the bulk value of α-Fe and are substantially higher than other transition metal and Fe based magnetic materials, e.g., oxide and ferrites. The high magnetization and optimality of TC values for self-controlled hyperthermia applications observed in these materials distinguish them as magnetic material of choice for such applications.

Fabrication and magnetic properties of patterned NiFeMo films electrodeposited in self-assembled nanosphere templates