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
Waste from paper and pulp industry supplies raw material for development of new redox flow batteries
12.10.2017 | Johannes Gutenberg-Universität Mainz
Low-cost battery from waste graphite
11.10.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research