Wisconsin Alumni Research Foundation

Other

Chang-Beom Eom

Daesu Lee

Jungwoo Lee

Tianxiang Nan

Zhenqiang Ma

Dong Liu

Sang June Cho

Jaeseong Lee

Thomas Francis Kuech

Darrell G Schlom

Paul Gregory Evans

Donald E Savage

Jiamian Hu

Shihao Zhuang

Shane Martin Lindeman

Ho Won Jang

Kyung-Jin Choi

Long-Qing Chen

Rui Liu

Jonathon Schad

Mark Steven Rzchowski

Jieun Kim

Hyungwoo Lee

Julian James Irwin

Trevor Jeffrey Anderson

Optoelectronic transducers that convert a femtosecond (fs)-timescale laser pulse into an a.c. electrical current pulse with an extremely high frequency and a high quality factor (Q) are provided. Both the frequency and amplitude of the a.c. electrical current pulse can be dynamically tuned by the application of a varying bias magnetic field. The optoelectronic transducers are based on a trilayered freestanding membrane that functions as both an acoustic cavity and a magnon cavity. The freestanding membrane includes an electrical conductor layer, a magnetic insulator layer, and a dielectric layer arranged in a vertical stack.

Magnetic-field-tunable terahertz optoelectronic transducer

Apparatus and methods for growing films of complex layered metal oxides with high stoichiometries and high crystal qualities are provided. The layered complex metal oxides include two or more metals and oxygen and have a layered structure. The methods, which are referred to as hybrid pulsed laser deposition (hybrid PLD), synergistically combine the advantages of molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) to grow complex metal oxide films that include metals with very different vapor pressures.

Hybrid pulsed laser deposition of complex oxide thin films made from elements having a large vapor pressure mismatch

Voltage-controlled spin field effect transistors ('spin transistors') and methods for their use in switching applications are provided. In the spin transistors, spin current is transported from a spin injection contact to a spin detection contact through a multiferroic antiferromagnetic channel via magnon propagation. The spin current transport is modulated by the application of a gate voltage that increases the number of domain boundaries the multiferroic antiferromagnetic material.

Spin transistors based on voltage-controlled magnon transport in multiferroic antiferromagnets

Aluminum oxide (AlO) thin films having a high γ-phase purity and low defect density and methods for making the aluminum oxide thin films are provided. Also provided are epitaxial heterostructures that incorporate the aluminum oxide thin films as growth substrates and methods of forming the heterostructures. The AlOfilms are pure, or nearly pure, γ-AlO. As such, the films contain no, or only a very low concentration of, other AlOpolymorph phases. In particular, the AlOfilms contain no, or only a very low concentration of, the θ-AlOpolymorph phase.

Low-defect-density gamma phase aluminum oxide substrates for heteroepitaxial synthesis

Methods and systems for forming complex oxide films are provided. Also provided are complex oxide films and heterostructures made using the methods and electronic devices incorporating the complex oxide films and heterostructures. In the methods pulsed laser deposition is conducted in an atmosphere containing a metal-organic precursor to form highly stoichiometric complex oxides.

Metal-organic pulsed laser deposition for stoichiometric complex oxide thin films

Heterostructures that include a bilayer composed of epitaxial layers of vanadium dioxide having different rutile-to-monoclinic phase transition temperatures are provided. Also provided are electrical switches that incorporate the heterostructures. The bilayers are characterized in that they undergo a single-step, collective, metal-insulator transition at an electronic transition temperature. At temperatures below the electronic transition temperature, the layer of vanadium dioxide having the higher rutile-to-monoclinic phase transition temperature has an insulating monoclinic crystalline phase, which is converted to a metallic monoclinic crystalline phase at temperatures above the electronic transition temperature.

Vanadium dioxide heterostructures having an isostructural metal-insulator transition

Magnetoelectric devices based on piezoelectric/magnetostrictive bilayers are provided. Also provided are methods of using the devices to modulate or to sense the magnetization of the magnetostrictive material. The devices include an island of magnetostrictive material that is strain-coupled to a thin layer of a piezoelectric material at an interface. A bottom electrode is placed in electrical communication with one surface of the piezoelectric film, and an unpaired top electrode is placed in electrical communication with a second, opposing surface of the piezoelectric film.

Anisotropic strain-driven magnetoelectric devices

Spintronic devices based on metallic antiferromagnets having a non-collinear spin structure are provided. Also provided are methods for operating the devices. The spintronic devices are based on a bilayer structure that includes a spin torque layer of an antiferromagnetic material having a non-collinear triangular spin structure adjoining a layer of ferromagnetic material.

Non-collinear antiferromagnets for high density and low power spintronics devices

Switches for electromagnetic radiation, including radiofrequency switches and optical switches, are provided. Also provided are methods of using the switches. The switches incorporate layers of high quality VOthat are composed of a plurality of connected crystalline VOdomains having the same crystal structure and orientation.

Vanadium dioxide-based optical and radiofrequency switches

Oxide heterostructures that form spatially separated electron-hole bilayers are provided. Also provided are electronic devices that incorporate the oxide heterostructures. The oxide heterostructure includes a base layer of SrTiO, a polar layer of LaAlO, and a non-polar layer of SrTiO. Within the oxide heterostructures, a two-dimensional hole gas (2DHG) is formed at the interface between the non-polar layer and the polar layer and a two-dimensional electron gas (2DEG) is formed at the interface between the polar layer and the base layer.

Oxide heterostructures having spatially separated electron-hole bilayers

Magnetic switching devices, including magnetic memory devices, are provided. The devices use high-quality crystalline films of 4d or 5d transition metal perovskite having a strong spin-orbit coupling (SOC) to produce spin-orbit torque in adjacent ferromagnetic materials via a strong spin-Hall effect. Spin-orbit torque can be generated by the devices with a high efficiency, even at or near room temperature.

Magnetic memory devices based on 4D and 5D transition metal perovskites

Layers of high quality VOand methods of fabricating the layers of VOare provided. The layers are composed of a plurality of connected crystalline VOdomains having the same crystal structure and the same epitaxial orientation.

Growing community of inventors

Madison, WI, United States of America

Chang-Beom Eom