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Displaying 1 - 25 of 240

Challenges for Sub-PicoTesla Magnetic-Tunnel-Junction Sensors

October 12, 2021
Author(s)
Robert McMichael, Philip Pong, John Unguris, William F. Egelhoff Jr., A Edelstein, E Nowak, Sean R. Parkin
The extension of small, inexpensive, low-power magnetic sensors into the sub-picoTesla regime, which is currently dominated by fluxgates and SQUIDS, would be a paradigm shift for the field of magnetic sensors. The necessary elements for sub-picoTesla MTJ

Magnetic depth profiling Co/Cu multilayers to investigate magnetoresistance

October 12, 2021
Author(s)
John Unguris, D. Tulchinsky, Michael H. Kelley, Julie Borchers, Joseph Dura, Charles Majkrzak, S. Y. Hsu, R. Loloee, W. P. Pratt, J. Bass
The magnetic microstructure responsible for the metastable high resistance state of weakly coupled, as-prepared [Co(6nm)/Cu(6nm)] 20 multilayers was analyzed using polarized neutron reflectivity and scanning electron microscopy with polarization analysis

Bubble magnetometry of nanoparticle heterogeneity and interaction

June 7, 2019
Author(s)
Andrew L. Balk, Ian J. Gilbert, R. Ivkov, John Unguris, Samuel Stavis
Bubbles have a rich history as transducers in particle-physics experiments. In a solid-state analogue, we use bubble domains in nanomagnetic films to measure magnetic nanoparticles. This technique can determine the magnetic orientation of a single

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

Spatially resolved ferroelectric domain-switching-controlled magnetism in Co 40 Fe 40 B 20 /Pb(Mg 1/3 Nb 2/3 ) 0.7 Ti 0.3 O 3 multiferroic heterostructure

December 27, 2016
Author(s)
Peisen Li, Yonggang Zhao, Sen Zhang, Aitian Chen, Dalai Li, Jing Ma, Yan Liu, Daniel T. Pierce, John Unguris, Hongguang Piao, Huiyun Zhang, Meihong Zhu, Xiaozhong Zhang, Xiufeng Han, Mengchun Pan, Ce-Wen Nan
Intrinsic spatial inhomogeneity or phase separation in cuprates and manganites etc., related to electronic and/or magnetic properties, has attracted much attention due to its significance in fundamental physics and applications. Here we use scanning Kerr

Magnetic microscopy and simulation of strain-mediated control of magnetization in Ni/PMN-PT nanostructures

October 17, 2016
Author(s)
Ian J. Gilbert, Andres C. Chavez, Daniel T. Pierce, John Unguris, Wei-Yang Sun, Cheng-Yen Liang, Gregory P. Carman
Strain-mediated thin film multiferroics comprising piezoelectric/ferromagnetic heterostructures enable the electrical manipulation of magnetization with much greater efficiency than other methods; however, the investigation of nanostructures fabricated

Nanoscale imaging of magnetization reversal driven by spin-orbit torque

September 23, 2016
Author(s)
Ian J. Gilbert, Andrew P. Chen, Daniel B. Gopman, Andrew L. Balk, Daniel T. Pierce, Mark D. Stiles, John Unguris
We use scanning electron microscopy with polarization analysis (SEMPA) to image deterministic, spin-orbit torque driven magnetization reversal of in-plane magnetized CoFeB rectangles in zero applied magnetic field. The spin-orbit torque is generated by

Direct imaging of coexisting ordered and frustrated sublattices in artificial ferromagnetic quasicrystals

April 25, 2016
Author(s)
Barry Farmer, Vinayak Bhat, Andrew L. Balk, Eric Teipel, Nathan Smith, John Unguris, D.J. Keavney, Todd Hastings, L .E. De Long
Quasicrystals are rarely found in nature and are difficult to grow in the laboratory, but exhibit unique physical properties resulting from their signature long-range structural order without periodic translational symmetry. Magnetic interactions in

Realization of Ground-State Artificial Skyrmion Lattices at Room Temperature

October 8, 2015
Author(s)
Dustin A. Gilbert, Brian B. Maranville, Andy L. Balk, Brian J. Kirby, Peter Fischer, Daniel T. Pierce, John Unguris, Julie A. Borchers, Kai Liu
The topological nature of magnetic skyrmions deriving from broken symmetries leads to extraordinary static and dynamic properties that provide new insight in fundamental problems of magnetism and exciting potentials for exploitation in novel magnetic