SCIENCE AND TECHNOLOGY OF SELF-ASSEMBLED MAGNETIC AND SUPERCONDUCTING NANO ARRAYS

Dhananjay Kumar, North Carolina Agricultural & Technical State University, DMR 0403480

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Coercivity of FeCo nanoparticles in TiN matrix as a function of number of laser pulses (directly related to particle size) at temperature indicated in the figure.

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Gd thin film (50 nm thick)

Ni MD nanoparticles (12 nm)

FePt nanoparticles (6 nm)

LPCMO

M/

Mm

ax

H/Hm

(T)

Ni SD nanoparticles (3nm)

Scaling collapse of hysteretic data occurs for a wide variety of thin-film magnetic systems when ΔM(T,H)/ΔMmax(T) is plotted against the normalized magnetic field H/Hm(T) . Notation: SD(MD) refers to single (multiple) domain nanoparticle systems (Ni embedded in AlOx host), LPCMO is a phase separated (La,Pr)CaMnO3 manganite, Gd (gadolinium) films are polycrystallline and do not contain nanoparticles. For each curve, the temperature increases from left to right at fixed field.

Schematic of formation of bonding and antibonding (*) molecular orbitals in FeCo molecule explaining the improvement in magnetic properties

Scaling collapse of the irreversible magnetization of various ferromagnetic thin films

SCIENCE AND TECHNOLOGY OF SELF-ASSEMBLED MAGNETIC AND SUPERCONDUCTING NANO ARRAYS

Dhananjay Kumar, North Carolina Agricultural & Technical State University, DMR 0403480

2009 REU students activties : 2 REU Teams

RESEARCH TRAINING AND DEVELOPMENT: Over 10 undergraduate students, 5 graduate students, and several other researchers have worked with NIRT supported faculties and or NIRT supported research equipments. We have also developed two new courses that are related to nanoscience and in the department of Mechanical and Chemical Engineering. These courses are: (i) MEEN 685-Fundamentals of Nanoscience and Engineering and (ii) MEEN 785: Nanomaterials.

Nanomaterials class visiting ORNL. Lectures by ORNL scientists (top), socialization, and visiting labs (bottom) were part of this trip.

Publications and presentations: Applied Physics Letters 94, 151913 (2009), AppliedPhysics Letters 94, 012510 (2009), Acta Materialia, 57, 2040-2046 (2009), Applied Physics Letters,93, 133105 (2008), Nanoscience and Nanotechnology, p. 1, vol. 8, (2008), Nano Letters, p. 1016,

vol.8, (2008), Journal of Applied Physics, p. 073910, vol. 104, (2008), Journal of Physics CondensedMatter, p. 385213, vol. 20, (2008), Applied Physics Letters, p. 042506, vol. 93, (2008), Applied

PhysicsLetters, p. 102504, vol. 92, (2008), Applied Physics Letters, p. 082507, vol. 93, (2008).