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Search Publications by: Robert D. Shull (Assoc)

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Displaying 1 - 25 of 94

Magnetoelastic effects in doubly clamped electroplated CoFe micro-beam resonators

March 12, 2019
Author(s)
Margo Staruch, S. P. Bennett, B. R. Matis, J. W. Baldwin, K. Bussmann, Daniel Gopman, Yury Kabanov, June W. Lau, Robert D. Shull, E. Langlois, C. Arrington, J. R. Pillars, Peter Finkel
Magnetostrictive Co77Fe23 films were fabricated on silicon wafers and fully suspended to produce free-standing, doubly clamped, micro-beam resonators. A negative or positive shift in the resonant frequency was observed for magnetic fields applied parallel

Electric-field control of perpendicular magnetic anisotropy in multiferroic PZT- and PMN- PT//[Co/Ni] composites with negative magnetostriction

July 4, 2018
Author(s)
Daniel B. Gopman, Andrew P. Chen, Cindi L. Dennis, June W. Lau, Robert D. Shull, Gregory P. Carman, Peter Finkel, Margo Staruch, Andres Chavez
A longstanding goal of spintronics is to identify alternatives to current-generated Oersted- fields for magnetization control at the nanoscale. An emerging approach seeks to harness the voltage-induced strain in a proximal piezostrictive layer to modify

Zero-field current switching of magnetic domains via chiral domain walls

March 16, 2018
Author(s)
Yufan Li, Qinli Ma, Daniel Gopman, Yury Kabanov, Robert D. Shull, C Chien
In ferromagnetic (FM) materials, the inherent exchange interaction, magnetic anisotropy, & dipolar forces dictate the domain walls (DWs), Bloch or N´eel, that separate magnetic moments. However, in FM thin films in contact with heavy metal (HM) with strong

Large magneto-optical Kerr effect and real-time imaging of magnetic domain in an antiferromagnet

January 26, 2018
Author(s)
Daniel B. Gopman, Robert D. Shull, Yury Kabanov, Huiyan Man, L. Wu, O.M.J. van 't Erve, D. Rees, Yufan Li, S. Pantakar, C L. Chien, J Orenstein, Tomoya Higo, Satoru Nakatsuji
When a linearly polarized light beam is incident upon the surface of a magnetic material, the reflected light becomes elliptically polarized and the ellipse major axes undergo a polar rotation within the polarization plane of the incident light: this

Electric-Field Induced Reversible Switching of the Magnetic Easy Axis in Co/BiFeO 3 on SrTiO 3

April 18, 2017
Author(s)
Tieren Gao, Xiaohang Zhang, William D. Ratcliff, Shingo Maruyama, Makoto Murakami, Anbusathaiah Varatharajan, Zahra Yamani, Peijie Chen, Ke Wang, Huairuo Zhang, Robert D. Shull, Leonid A. Bendersky, John Unguris, R. Ramesh, Ramamoorthy Ramesh, I. Takeuchi
We demonstrate reversible electric-field-induced switching of the magnetic state of the Co layer in Co/BiFeO 3 (BFO) (001) thin film heterostructures fabricated on (001) SrTiO 3 substrates. The angular dependence of the coercivity and the remanent

Manipulation of magnetic anisotropy through linear piezoelectric response in magnetoelectric heterostructures

November 21, 2016
Author(s)
Daniel B. Gopman, Robert D. Shull, Yury Y. Iunin, Margo Staruch, Shu-Fan Cheng, Konrad Bussmann, Peter Finkel
The ability to tune both magnetic and electric properties concomitantly in magnetoelectric (ME) composite heterostructures coupled through interfacial strain is crucial for multiple transduction applications including energy harvesting or magnetic field

Influence of internal geometry on magnetization reversal in asymmetric permalloy rings

August 28, 2016
Author(s)
Daniel B. Gopman, Yury Kabanov, Robert D. Shull, Jizhai Cui, Christopher Lynch
We report the magnetization reversal behavior of microstructured $\mathrm{Ni_{80}Fe_{20}}$ rings using magneto-optic indicator film imaging and magnetometry. While the reversal behavior of rings with a symmetric (circular) interior hole agree with

Effect of Grain Constraint on the Field Requirements for Magnetocaloric Effect in Ni(sub45)Co(Sub5)Mn(Sub40)Sn(sub10) Melt-Spun Ribbons

August 21, 2016
Author(s)
N. M. Bruno, Y. J. Huang, Cindi L. Dennis, J. G. Li, Robert D. Shull, J. H. Ross Jr., Y. I. Chumlyakov, I. Karaman
The influence of grain constraint on the magnetic field levels required to complete the isothermal martensitic transformation in magnetic shape memory alloys has been demonstrated for a NiCoMnSn alloy and the magnetocaloric performance of an optimally heat

Kondo Effect in Magnetic Tunnel Junctions with an AIOx Tunnel Barrier

June 17, 2016
Author(s)
Chao Zheng, Robert D. Shull, Andrew P. Chen, Philip Pong
The Kondo effect in magnetic tunnel junctions (MTJs) is a result of the spin-exchange interaction between magnetic impurities and the conduction electrons. The presence of the Kondo effect can strongly influence the spin-dependent transport behavior of

Shape critical properties of patterned Permalloy thin films

December 7, 2015
Author(s)
Robert D. Shull, Y. P. Kabanov, V S. Gornakov, Andrew P. Chen, Valerian I. Nikitenko
The effects of shape and edges in magnetic elements with reduced dimensions on the magnetization reversal of cross- and framed cross- shaped Ni(sub79)Fe(sub21) (30mn) films were studied. Remagnetization details in the stripes of the patterned structures

Magnetocaloric Response Of Non-Stoichiometric Ni(sub2)MnGa Alloys and the Influence of Texture

November 1, 2015
Author(s)
Michael V. McLeod, Anit Giri, Brigitte A. Paterson, Cindi L. Dennis, H L. Zhou, S C. Vogel, Yong Ho Sohn, Robert D. Shull, B S. Majumdar
Currently, there is significant interest in magnetocaloric materials for solid state refrigeration. In this work, polycrystalline Heusler alloys belonging to the Ni(sub2+x)Mn(sub 1-x) Ga family, with x between 0.08 and 0.24, were evaluated for the purpose

Gd(sub 90)Co(sub 2.5)Fe(sub 7.5) Alloy Displaying Enhanced magnetocaloric Properties

July 3, 2015
Author(s)
Virgil Provenzano, Robert D. Shull, G Kletetschka, Paul E. Stutzman
Because of its attractive magnetocaloric properties, gadolinium (Gd) metal is currently the refrigerant of choice in the development of near-room temperature magnetic cooling prototypes (refrigerators, heat pumps, and air conditioners). The overwhelming

Details of the Magnetization Reversal in Patterned Exchange-biased and Unbiased Thin Films

November 1, 2014
Author(s)
Robert D. Shull, Y. P. Kabanov, Andrew P. Chen, Cindi L. Dennis, V S. Gornakov, Valerian I. Nikitenko
New features of the magnetization reversal of a patterned bilayer in the form of a square mesh consisting of 16 um wide intersecting stripes of Ni(sub79)Fe(sub21) (30 nm) exchange-coupled with IrMn (10 um) on top were revealed via use of the advanced

International comparison of measurements of hard magnets with the Vibrating Sample Magnetometer

August 1, 2014
Author(s)
F. Fiorillo, C. Beatrice, D. Son, Franz Josef Ahlers, R. Groessinger, F. Albertini, Y. P. Liu, A Lin, E. Patroi, Robert D. Shull, O. Thomas
We present the results of an international comparison regarding the magnetic properties of hard magnets, measured using the Vibrating Sample Magnetometer. The comparison involved eight different international laboratories, plus two laboratories using the

Radiation Studies of Spin-transfer Torque Materials and Devices

August 15, 2013
Author(s)
H. L. Hughes, Konrad Bussmann, Shu-Fan Cheng, Robert D. Shull, Andrew P. Chen, S. Schafer, T. Mewes, A. Ong, E. N. Chen
Spin-transfer torque film stacks and devices having in-plane magnetization were irradiated using a cobalt-60 gamma source. The film stacks have a biased, synthetic antiferromagnet spin-valve architecture. Measurements of magnetization vs. field

Use of Half Metallic Heusler Alloys in CoFeB/MgO/Heusler Alloy Tunnel Junctions

July 15, 2013
Author(s)
Andrew P. Chen, Gen G. Feng, Robert D. Shull
Heusler Alloys Co(sub2)FeSi and Co(sub2)MnSi were deposited on both single crystal MgO (100) and polycrystalline SiO(Sub2) silicon thermal oxide substrates and characterized by x-ray diffraction before and after thermal annealing at various temperatures

Direct Experimental Study of the Effect of Dislocations on the Magnetization Reversal in a Quasi-Two- Dimensional Ferromagnet with Unidirectional Anisotropy

May 15, 2013
Author(s)
V S. Gornakov, Valerian I. Nikitenko, I. V. Shashkov, M. A. Lebyodkin, Robert D. Shull
The effect of dislocations on the elementary acts of the magnetization reversal in the epitaxial heterostructure NiFe/NiO/MgO(001) has been studied using the magneto-optical indicator film technique. It has been found that the edge dislocations grouped