Magnetic property changes by several hundred percent over a narrow temperature range.
Image courtesy of Ivan Schuller, University of California, San Diego
The magnetic coercivity, the resistance to change in the orientation of the magnetic domain structure, for nickel (Ni) was shown to strongly depend on the crystal structure of the underlying oxide (vanadium oxide). The maximum Ni coercivity occurs at the peak of the oxide’s metal insulator transition.
Proximity effects in hybrid heterostructures, which contain distinct layers of different materials, allow one material species to reveal and/or control properties of a dissimilar species. Specifically, for a magnetic thin film deposited onto a transition metal oxide film, the magnetic properties change dramatically as the oxide undergoes a structural phase transition.
The hybrid between a simple magnetic material and a transition-metal oxide provides a “window” to understand the metal-to-insulator transition and offers dramatic tunability of magnetic properties. Potential applications are envisioned in the fields of information storage and power transmission.
Novel effects are increasingly being discovered when dissimilar materials are in contact (“hybrids”), often resulting in altogether new phenomena, materials with useful functionalities, or the ability to sense or control important material properties.
The focus of this investigation is a hybrid material consisting of a thin nickel film on a vanadium oxide substrate; this hybrid material exhibits magnetic properties unlike any other magnetic material. In this case, the magnetic coercivity (defined as the resistance to a change in the direction of the magnetic fields for a ferromagnetic material) of the nickel reveals insights concerning the transition of the vanadium oxide from being an electrical conductor to becoming an insulator, called the metal-insulator transition (MIT). In turn, the MIT can be used to control the coercivity of the nickel.
The vanadium oxide MIT is coincidental with a structural change at a well-defined “transition” temperature. At the thermal midpoint of the transition, crystallites of both phases coexist in equal portions, resulting in maximal structural entropy. The resulting inhomogeneity of the oxide structure causes stresses in the nickel (or other magnetic) film deposited on top. This provides a strong link between the nickel coercivity and the disorder in the oxide.
The coercivity is low when the oxide is structurally uniform (above and below the MIT) and high when it is maximally disordered in the middle of the transition. The magnetic properties of nickel therefore provide a window into the MIT process.
In turn, the MIT allows dramatic nonmagnetic control of the coercivity, which changes by several hundred percent within a narrow 10 K temperature range, unlike any other known magnetic material. Potential applications have been envisioned in two important, disparate energy related fields: energy driven magnetic recording and self-healing current fault limiters.
DOE Office of Science, Basic Energy Sciences (magnetism aspects) and the Air Force Office of Scientific Research (oxide-related research).
J. de la Venta, S. Wang, T. Saerbeck, J.G. Ramirez, I. Valmianski, I.K. Schuller, “Coercivity enhancement in V2O3/Ni bilayers driven by nanoscale phase coexistence.” Applied Physics Letters 104, 062410 (2014). [DOI: 10.1063/1.4865587]
Kristin Manke | newswise
Nano-scale process may speed arrival of cheaper hi-tech products
09.11.2018 | University of Edinburgh
Nuclear fusion: wrestling with burning questions on the control of 'burning plasmas'
25.10.2018 | Lehigh University
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Health and Medicine
16.11.2018 | Life Sciences
16.11.2018 | Life Sciences