New Publication!- P. B. Meisenheimer, S. Novakov, N. M. Vu, J. T. Heron  Journal of Applied Physics 123, 240901 (2018).

Abstract: Since the resurgence of multiferroics research, significant advancement has been made in the theoretical and experimental investigation of the electric field control of magnetization, magnetic anisotropy, magnetic phase, magnetic domains, and Curie temperature in multiferroic heterostructures. As a result of these advances, multiferroic heterostructures are on a trajectory to impact spintronics applications through the significantly reduced energy consumption per unit area for magnetization switching (1–500 μJ cm⁻²) when compared to that of current-driven magnetization switching (0.2–10 mJ cm⁻²). Considering this potential impact, it becomes necessary to understand magnetoelectric switching dynamics and characteristic switching times. The body of experimental work investigating magnetoelectric switching dynamics is rather limited, with the majority of room temperature converse magnetoelectric switching measurements reported having employed relatively long voltage pulses. Recently, however, the field has started to consider the kinetics of the switching path in multiferroic (and ferroelectric) switching. Excitingly, the results are challenging our understanding of switching processes while offering new opportunities to engineer the magnetoelectric effect. Considering the prospects of multiferroics for beyond-CMOS applications and the possible influence on operational speed, much remains to be understood regarding magnetoelectric switching kinetics and dynamics, particularly at reduced dimensions and under the influence of boundary effects resulting from strain, electrostatics, and orientation. In this article, we review magnetoelectric switching in multiferroic heterostructures for the electric field control of magnetism. We then offer perspectives moving toward the goal of low energy-delay spintronics for computational applications.

Full text available from Journal of Applied Physics

New Publication!- S. Sivakumar*, E. Zwier*, P. B. Meisenheimer*, J. T. Heron J. Vis. Exp. (135), e57746, (2018).

Abstract: Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (Cu variant) entropy-stabilized oxides. Phase pure and chemically homogeneous (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (x = 0.20, 0.27, 0.33) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (x = 0.11, 0.27) ceramic pellets are synthesized and used in the deposition of ultra-high quality, phase pure, single crystalline thin films of the target stoichiometry. A detailed methodology for the deposition of smooth, chemically homogeneous, entropy-stabilized oxide thin films by pulsed laser deposition on (001)-oriented MgO substrates is described. The phase and crystallinity of bulk and thin film materials are confirmed using X-ray diffraction. Composition and chemical homogeneity are confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The surface topography of thin films is measured with scanning probe microscopy. The synthesis of high quality, single crystalline, entropy-stabilized oxide thin films enables the study of interface, size, strain, and disorder effects on the properties in this new class of highly disordered oxide materials.

Full text available from Journal of Visualized Experiments

New Publication!- R. Iraei, N. Kani, S. Dutta, D. E. Nikonov, S. Manipatruni, I. A. Young, J. T. Heron, and A. Naeemi, Clocked Magnetostriction-Assisted Spintronic Device Design and Simulation, IEEE Trans. Electronic Devices 65, 5(2017).

Abstract: We propose a heterostructure device comprised of magnets and piezoelectrics, which significantly improves the delay and the energy dissipation of an all-spin logic (ASL) device. This paper studies and models the physics of the device, illustrates its operation, and benchmarks its performance using SPICE simulations. We show that the proposed device maintains low-voltage operation, nonreciprocity, nonvolatility, cascadability, and thermal reliability of the original ASL device. Moreover, by utilizing the deterministic switching of a magnet from the saddle point of the energy profile, the device is more efficient in terms of energy and delay and is robust to thermal fluctuations. The results of simulations show that compared to ASL devices, the proposed device achieves 21x shorter delay and 27x lower energy dissipation per bit for a 32-bit arithmetic-logic unit.

Full text available from IEEE Transactions on Electronic Devices.

Peter will be working in the Ferroelectronics Lab over the summer as part of the Summer Undergraduate Research in Engineering Program (SURE). SURE offers summer research internships to outstanding undergraduate students who have completed their sophomore or junior year. The progam funds the undergraduate student for 10-12 weeks of full-time research. Peter will be working to synthesize ordered antiferromagnetic Tb₂Ir₂O₇ thin films for use in magnetotransport studies.

Steve and Nguyen both received Rackham Graduate Student Research grants for $3,000 each. Steve’s grant will go towards buying a new magnetron sputtering assembly for the lab and Nguyen’s grant was for the purchase of a high voltage amplifier unit for electronic measurements. Congratulations to both of them.