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Search Publications by: Robert D. McMichael (Assoc)

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Displaying 1 - 25 of 314

Spectroscopy of photoionization from the 1E singlet state in nitrogen-vacancy centers in diamond

October 17, 2024
Author(s)
Sean Blakley, Thuc Mai, Stephen Moxim, Jason Ryan, Adam Biacchi, Angela Hight Walker, Robert McMichael
The 1E—1A1 singlet manifold of the negatively charged nitrogen vacancy (NV −) center in diamond plays a central role in the quantum information and quantum sensing applications of the NV − center. However, the energy of this manifold within the diamond

Simplified algorithms for adaptive experiment design in parameter estimation

November 1, 2022
Author(s)
Robert D. McMichael, Sean Blakley
In experiments to estimate parameters of a parametric model, Bayesian experiment design allows measurement settings to be chosen based on utility, i.e. the predicted improvement of parameter distributions due to modeled measurement results. In this paper

Robust spin relaxometry with fast adaptive Bayesian estimation

June 15, 2022
Author(s)
Michael Caouette-Mansour, Adrian Solyom, Brandon Ruffolo, Robert D. McMichael, Jack Childress (Sankey), Lilian Childress
Spin relaxometry with nitrogen-vacancy (NV) centers in diamond offers a spectrally selective, atomically localized, and calibrated measurement of microwave-frequency magnetic noise, presenting a versatile probe for condensed matter and biological systems

Advances in Magnetometry Through Miniaturization

October 12, 2021
Author(s)
A Edelstein, J Burnette, Greg Fischer, S F. Cheng, William F. Egelhoff Jr., Robert McMichael, E Nowak
Recent innovations may lead to magnetic sensors that are smaller, more sensitive and/or cost less than current magnetometers. Examples of this are the chip scale atomic magnetometer, magnetic tunnel junctions with MgO barriers, and a device for minimizing

Annealing Temperature Dependences of Magnetization Reversal in Exchange Biased Bilayers

October 12, 2021
Author(s)
C G. Lee, V S. Gornakov, B H. Koo, K S. Shin, Robert McMichael, Andrew P. Chen, William F. Egelhoff Jr.
The thermal stability of the hysteretic properties and domain structures of exchange-coupled Co-Fe/Ir-Mn and Ni-Fe/Ir-Mn bilayers was studied. Using the magneto-optical indicator film technique, X-ray diffractometry, and VSM, we have revealed that the

Artifacts That Could Be Misinterpreted as Ballistic Magnetoresistance

October 12, 2021
Author(s)
William F. Egelhoff Jr., L Gan, Erik B. Svedberg, Cedric J. Powell, Alexander J. Shapiro, Robert McMichael, J Mallett, Thomas P. Moffat, Mark D. Stiles
Theoretical physics suggests that very large magnetoresistance (MR) values might be found in certain magnetic nanocontacts if a magnetic domain wall could be localized in them with a length scale that would allow conduction electrons to transit the wall

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

Composition-based Reduction of Damping in Fe1-xVx (50nm) Thin Films

October 12, 2021
Author(s)
L Cheng, H Song, J O. Rantschler, Robert McMichael, William E. Bailey
The reduction of GHz damping a is a critical and unaddressed need in ferromagnetic materials development. Smith has predicted that the signal-to-noise ratios of nanoscale / Ghz spin electronic sensors will be inversely dependent on the free magnetic layer

Ferromagnetic Resonance Line Width in Inhomogeneous Thin Films

October 12, 2021
Author(s)
Robert McMichael, A B. Kunz, D J. Twisselmann
The dynamic properties of magnetic materials are important for magnetic data storage. The primary measurement technique for understanding magnetization damping is ferromagnetic resonance line width. Because materials inhomogeneities increase experimental

The Suppression of Orange-Peel Coupling in Magnetic Tunnel Junctions by Pre-Oxidation

October 12, 2021
Author(s)
William F. Egelhoff Jr., Robert McMichael, Cindi L. Dennis, Mark D. Stiles, Alexander J. Shapiro, Brian B. Maranville, Cedric J. Powell
We have have found that pre-oxidation of the bottom Co electrode in magnetic tunnel junctions (MTJs) very effectively suppresses orange-peel coupling. The result is a free layer that is much softer. Work by others has demonstrated that pre-oxidation is

Thin Film Edge Property Measurements by Edge Saturation

October 12, 2021
Author(s)
Brian B. Maranville, Robert McMichael, Cindi L. Dennis, C A. Ross, J Cheng
Two techniques are described for characterizing the magnetic properties of the edges in long, straight magnetic stripes, using vector magnetometry. The critical transverse field at which the edge magnetization saturates is determined by measuring

Sequential Bayesian experiment design for adaptive Ramsey sequence measurements.

October 11, 2021
Author(s)
Robert D. McMichael, Sergey Dushenko, Sean Blakley
The Ramsey sequence is a canonical example of a quantum phase determination for a spin qubit, but when readout fidelity is low, as with NV centers, measurement efficiency can be increased by focusing measurement resources on the most productive settings