U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by: Robert D. Shull (Assoc)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 26 - 50 of 94

Influence of Pt spacer thickness on the domain nucleation in ultrathin Co/Pt/Co trilayers

May 1, 2013
Author(s)
Robert D. Shull, Yury Y. Iunin, Y. P. Kabanov, Valerian I. Nikitenko, O. V. Skryabina, C. L. Chien
The effect of varying the interlayer coupling between two 0.6 nm thick Co layers with perpendicular anisotropy on their magnetic ground state and the domain nucleation processes during a field reversal was studied. A surprising transition from out-of-plane

Ferri- to ferro-magnetic transition in the martensitic phase of a Heusler alloy

September 15, 2012
Author(s)
Robert D. Shull, Lawrence H. Bennett, Virgil Provenzano, Y. N. Jin, Igor Levin, E. Della Torre
During the past decade the magnetic properties of Heusler alloys have been extensively studied, motivated in part by the observation of large magnetocaloric effect (MCE) peaks displayed by these alloys near room temperature. We present new data and

Controlling High Coercivities of Ferromagnetic Nanowires Encapsulated in Carbon Nanotubes

June 15, 2010
Author(s)
Robert D. Shull, Cindi L. Dennis, A. Morelos-Gomez, Florentino N. Lopez-Urias, Emilio N. Munoz-Sandoval, H. Terrones, M. Terrones
Cylindrical ferromagnetic nanowires encapsulated inside multiwalled carbon nanotubes (MWNTs) are synthesized by pyrolizing either ferrocene powder or ferrocene-toluene mixtures. By changing the way the precursor is thermolyzed, we have been able to control

Clifford Glenwood Shull

March 31, 2010
Author(s)
Robert D. Shull
In 1975 Clifford Glenwood Shull was elected to membership in the National Academy of Science. He had earlier, 1956, been admitted to the American Academy of Arts and Sciences, and would in 1994 be awarded the Nobel Prize in Physics. These and other honors

Direct Measurement of the Magnetocaloric Effect in Gd_5}Si_2}Ge_1.9}Ga_0.1}

March 19, 2010
Author(s)
E. N. Palacios, G. F. Wang, R. Burriel, Virgil Provenzano, Robert D. Shull
Doping with some metals (Fe, Cu, Ga, Mn, Al) reduces or removes the strong thermal hysteresis in the giant magnetocaloric alloys Gd_5}Si_x}Ge_1-x}_4}. We present heat capacity and direct measurements of the isothermal entropy change, ¢ST , and adiabatic

Vertically Graded Anisotropy in Co/Pd Multilayers

March 8, 2010
Author(s)
Brian J. Kirby, Joseph E. Davies, Kai Liu, Shannon Watson, G. T. Zimanyi, Robert D. Shull, Paul A. Kienzle, Julie A. Borchers
It has been theoretically predicted that depth-grading the magnetic anisotropy in perpendicular magnetic media should reduce the field required to write data, without affecting the thermal stability. To study this prediction, we have produced a series of

Magnetic Properties of Zr_(9)Ni_(11)Intermetallic Compound

February 7, 2010
Author(s)
Virgil Provenzano, Robert D. Shull, Richard M. Waterstrat, Lawrence H. Bennett, Edward Della Torre, H. Seyoum
We report on a very interesting magnetic behavior in the intermetallic compound Zr_(9)Ni_(11), namely, (i) spin-glass behavior and (ii) fluctuations in magnetization versus temperature curves. The magnetic properties are consistent with structural results

Frustrated magnetization reversal in Co/Pt multilayer films

July 13, 2009
Author(s)
Joseph E. Davies, O Hellwig, Eric E. Fullerton, M. Winklhofer, Robert D. Shull, Kai Liu
The magnetization reversal behavior in Co/Pt multilayers with perpendicular anisotropy are studied by the first order reversal curve (FORC) method. In addition to the previously observed three stage reversal process where domains first nucleate, then

Probing the Growth and Aging of Colloidal Cobalt Nanoparticles

June 11, 2009
Author(s)
Guangjun Cheng, Cindi L. Dennis, Robert D. Shull, Angela R. Hight Walker
We have combined transmission electron microscopy (TEM) and magnetic measurements to characterize the growth of colloidal cobalt (Co) nanoparticles during synthesis and their subsequent stability in air. During the growth, TEM measurements have shown the

Dipolar Chains formed by synthesized cobalt nanocubes

May 11, 2009
Author(s)
Guangjun Cheng, Robert D. Shull, Angela R. Hight Walker
Cobalt nanocubes with an average edge length of 50 nm and the epsilon crystalline structure were synthesized via thermo-decomposition in 1,2-dichlorobenzene at 120 oC in the presence of the surfactants. These nanocubes form dipolar chains upon drying in

In-plane bias in a patterned ferromagnetic/antiferromagnetic bilayer

April 30, 2009
Author(s)
Yury P. Kabanov, Valerian I. Nikitenko, Oleg A. Tikhomirov, William F. Egelhoff Jr., Alexander J. Shapiro, Robert D. Shull
Exchange bias in bi- and multilayer magnetic systems is usually ascribed to the existence of transient magnetic structures at the interfaces between adjacent layers. Here, we report the observation of a similar phenomenon in the lateral direction

On the nature of asymetry of nucleation centers activity in ultrathin Co films and Co/Pt multilayers

January 14, 2008
Author(s)
Yu L. Iunin, Yury P. Kabanov, Valerian I. Nikitenko, X M. Cheng, Alexander J. Shapiro, C L. Chien, Robert D. Shull
Magnetization reversal in ultrathin Pt(10 nm)/Co(0.6 nm)/Pt(3 nm) magnetic films and Pt(10 nm)/[Co(d)/Pt(1 nm)]_n}/ Pt(2 nm) (d = 0.4, 0.6, 0.8 nm, n = 2, 4) multilayers with perpendicular anisotropy has been studied using Kerr microscopy. These materials

Influence of the Colloidal Environment on the Magnetic Behavior of Cobalt Nanoparticles

November 6, 2007
Author(s)
Guangjun Cheng, Cindi L. Dennis, Robert D. Shull, Angela R. Hight Walker
The magnetic properties of 10 nm cobalt (Co) nanoparticles in 1,2-dicholorbenenze (DCB) are investigated via a series of magnetization (M) vs. temperature (T) measurements. A rapid rise in magnetization around 250 K during warming and a sudden drop at 240

Teaching Materials Science to Children, Ages 8-14

June 7, 2007
Author(s)
Robert D. Shull
A pre-high school science program, Adventure In Science (AIS), has been running in the Gaithersburg, Maryland area for the past 33 years. It s President, Dr. Robert D. Shull, a scientist in the Materials Science and Engineering Laboratory at the National

Asymmetrical Domain Nucleation and Unusual Magnetization Reversal of Ultrathin Co Films and Co/Pt Multilayers With Perpendicular Anisotropy

March 16, 2007
Author(s)
Yu L. Iunin, Yury P. Kabanov, Valerian I. Nikitenko, X M. Cheng, Alexander J. Shapiro, Robert D. Shull, C L. Chien
The features of magnetization reversal in Pt/[CO/Pt]_n}/Pt multilayers (n = 1, 2, 4) have been studied using magneto-optical Kerr microscopy. Asymmetric nucleation centers were revealed where domains form at different positions for up or down magnetic

Thermal Neutron Demagnetization of NdFeB Magnets

July 30, 2006
Author(s)
R Klaffky, Richard M. Lindstrom, Brian B. Maranville, Robert D. Shull, B Micklich, J Vacca
To isolate the effect that thermal neutrons have on Nd2Fe14B permanent magnets, the magnetization and coercivity were studied as a function of dose. The changes in remanent magnetization are substantial and are attributed to boron thermal neutron capture

The Effects of Small Metal Additions (Co, Cu, Ga, Mn, Al, Bi, Sn) on the Magnetocaloric Properties of the Gd 5 Ge 2 Si 2 Alloy

April 26, 2006
Author(s)
Robert D. Shull, Virgil Provenzano, Alexander J. Shapiro, A Fu, M W. Lufaso, E Karapetrova, G Kletetschka, V Mikula
It was shown that adding one atomic percent Fe to Gd5Ge2Si2 greatly reduced its large hysteresis losses, broadened the magnetic entropy change, ?Sm, versus temperature, T, peak, and shifted the ?Sm peak value from 275 K to 305 K[1]. The present paper

Unusual Magnetization Reversal in [Co/Pt]4 Multilayers With Perpendicular Anisotropy

April 21, 2006
Author(s)
X M. Cheng, Valerian I. Nikitenko, Alexander J. Shapiro, Robert D. Shull, C L. Chien
Unusual magnetization reversal of [Co(4 )/Pt(10 )]4 multilayers with perpendicular magnetic anisotropy has been revealed macroscopically by magnetometry measurements and microscopically by magneto-optical Kerr effect (MOKE) microscopy and magnetic force